Author response: Distinct regions of H. pylori’s bactofilin CcmA regulate protein–protein interactions to control helical cell shape
Year: 2022
Type: peer-review
Abstract: Article Figures and data Abstract Editor's evaluation Introduction Results Discussion Materials and methods Data availability References Decision letter Author response Article and author information Metrics Abstract The helical shape of Helicobacter pylori cells promotes robust stomach colonization; however, how the helical shape of H. pylori cells is determined is unresolved. Previous work identified helical-cell-shape-promoting protein complexes containing a peptidoglycan-hydrolase (Csd1), a peptidoglycan precursor synthesis enzyme (MurF), a non-enzymatic homolog of Csd1 (Csd2), non-enzymatic transmembrane proteins (Csd5 and Csd7), and a bactofilin (CcmA). Bactofilins are highly conserved, spontaneously polymerizing cytoskeletal bacterial proteins. We sought to understand CcmA’s function in generating the helical shape of H. pylori cells. Using CcmA deletion analysis, in vitro polymerization, and in vivo co-immunoprecipitation experiments, we identified that the bactofilin domain and N-terminal region of CcmA are required for helical cell shape and the bactofilin domain of CcmA is sufficient for polymerization and interactions with Csd5 and Csd7. We also found that CcmA’s N-terminal region inhibits interaction with Csd7. Deleting the N-terminal region of CcmA increases CcmA-Csd7 interactions and destabilizes the peptidoglycan-hydrolase Csd1. Using super-resolution microscopy, we found that Csd5 recruits CcmA to the cell envelope and promotes CcmA enrichment at the major helical axis. Thus, CcmA helps organize cell-shape-determining proteins and peptidoglycan synthesis machinery to coordinate cell wall modification and synthesis, promoting the curvature required to build a helical cell. Editor's evaluation This study addresses an important unresolved question, the mechanisms governing cell shape in a helical organism. Particularly exciting is the observation that a bactofilin – typically viewed as a cytoskeletal protein – plays a key role in modulating the balance between peptidoglycan synthesis and degradation necessary to generate the helical shape. These findings enhance our understanding of cell wall synthesis in bacteria generally, particularly with regard to the importance of local phenomena for cell shape generation. https://doi.org/10.7554/eLife.80111.sa0 Decision letter Reviews on Sciety eLife's review process Introduction Helicobacter pylori is a helical-shaped, Gram-negative bacteria that infects more than half of the world’s population (Hooi et al., 2017). Chronic infection with H. pylori can cause gastric ulcers and cancers; approximately 80% of gastric cancer cases are attributed to H. pylori infection (de Martel et al., 2020). The helical shape of H. pylori cells helps establish colonization of the stomach and promotes immunopathology during infection (Martínez et al., 2019; Montecucco and Rappuoli, 2001; Sycuro et al., 2010; Sycuro et al., 2012; Yang et al., 2019). Multiple proteins have been identified that are essential for the helical shape of H. pylori cells, most of which influence the shape and composition of the peptidoglycan (PG) sacculus directly or indirectly (Sycuro et al., 2010; Sycuro et al., 2013; Sycuro et al., 2012; Yang et al., 2019). Several cell-shape-determining (Csd) proteins form membrane-spanning protein complexes. Csd5 is a transmembrane protein that binds directly to PG in the periplasm with its SH3 domain and binds to CcmA in the cytoplasm. Csd5 also interacts with ATP synthase and MurF, an essential PG precursor enzyme that catalyzes the final cytoplasmic PG biosynthesis step, independent of interactions with CcmA (Blair et al., 2018; Hrast et al., 2013). Another complex is formed by Csd7, Csd1, and Csd2. Csd7 is a transmembrane protein that stabilizes the PG-hydrolase Csd1, and Csd2, a catalytically inactive homolog of Csd1. Weak interactions between Csd7 and CcmA have been detected by co-immunoprecipitation experiments that include cross-linking reagents followed by mass spectrometry (Yang et al., 2019), but whether CcmA, Csd7, and Csd5 are all part of one protein complex was unclear. CcmA and probes that report on PG synthesis localize to the major helical axis of H. pylori cells (regions with a Gaussian curvature value of 5 ± 1 µm–2 on a helical cell), indicating that CcmA is in the same region of the cell where increased levels of PG synthesis occur (Taylor et al., 2020). CcmA is the only bactofilin encoded in the H. pylori genome. Bactofilins are a class of highly conserved, spontaneously polymerizing, cytoskeletal proteins in bacteria that perform a variety of functions (Bulyha et al., 2013; El Andari et al., 2015; Lin et al., 2017; Osorio-Valeriano et al., 2019) including modulating cell shape in multiple different bacterial species (Brockett et al., 2021; Hay et al., 1999; Jackson et al., 2018; Koch et al., 2011; Sycuro et al., 2010) and morphogenesis of cell appendages (Billini et al., 2019; Caccamo et al., 2020; Kühn et al., 2010), both of which involve modification or synthesis of PG. But how a cytoplasmic bactofilin influences the PG cell wall in the periplasm is unclear. Bactofilins are identified by the presence of a bactofilin domain (DUF583), which forms a β-helix that is flanked by unstructured terminal regions. The function of the terminal regions and bactofilin domain of bactofilins are debated. It has been proposed that the terminal regions may be involved in modulating polymerization, binding to membranes and/or interacting with other proteins (Deng et al., 2019; Kühn et al., 2010; Vasa et al., 2015). However, experimental evidence to identify the function of the bactofilin domain and terminal regions of CcmA and other bactofilins is lacking. Here, we performed structure–function analysis to determine how the bactofilin domain and the terminal regions of CcmA contribute to generating the helical shape of H. pylori cells by evaluating cell morphology, CcmA polymerization and filament bundling, and interaction with known Csd protein interaction partners. Additionally, we identified how protein binding partners impact CcmA localization. We found that interactions between CcmA and other Csd proteins are responsible for CcmA’s ability to pattern the helical shape of H. pylori cells and identified that interactions between CcmA and its binding partners modulate CcmA localization and modulate protein stability of the PG-hydrolase Csd1. Together, these findings allow us to establish a new model for how H. pylori’s helical cell shape is generated. We clarify that CcmA participates in two separate helical-cell-shape-generating protein complexes. Additionally, these studies reveal that bactofilins can influence PG sacculus structure by modulating the protein stability of a PG hydrolase. Results CcmA is composed of a bactofilin domain and two short terminal regions To facilitate structure–function analysis of CcmA’s biochemical and cell biologic functions, we aligned the amino acid sequence of CcmA with BacA, a well-studied bactofilin from Caulobacter crescentus involved in stalk morphogenesis, using SWISS-MODEL (Waterhouse et al., 2018). This alignment revealed that CcmA is composed of a bactofilin domain (DUF 583) surrounded by two short terminal regions (Figure 1A). The N-terminal region is composed of amino acids 1–17, the bactofilin domain is composed of amino acids 18–118, and the C-terminal region is composed of amino acids 119–136. It has been proposed that bactofilins contain a short membrane binding motif within their N-terminal regions, which spans amino acids 3–12 in CcmA (Deng et al., 2019). However, whether the proposed membrane binding motif was functional in CcmA was unknown. Figure 1 Download asset Open asset Predicted structure of CcmA. (A) Sequence alignment between BacA from C. crescentus and CcmA from H. pylori generated with SWISS-MODEL; gray boxes indicate β-strands formed in the bactofilin domain, the green box indicates the N-terminal region of CcmA, and the pink box indicates the C-terminal region of CcmA. (B) Model of the bactofilin domain of CcmA generated by RoseTTAFold, which forms a right-handed, three-sided, triangular β-helix. (C) Five models of CcmA generated in RoseTTAFold displaying the bactofilin domain (gray), N-terminal region (green), and C-terminal region (pink). After identifying the boundaries between the bactofilin domain and the terminal regions of CcmA, we used RoseTTAFold (Baek et al., 2021), a protein structure prediction service that uses deep learning-based modeling methods, to predict the structure of CcmA. RoseTTAFold generated five models of CcmA. In all five, the bactofilin domain forms a three-sided, right-handed β-helix with a left-handed twist (Figure 1B), the N-terminal region is unstructured, and part of the C-terminal region forms a short ɑ-helix and caps the end of the bactofilin domain (Figure 1C). In four of the five models, the first several amino acids of the N-terminal region interact with the bactofilin domain, suggesting that the N-terminal region could potentially block a surface of the bactofilin domain. The N-terminal region and bactofilin domain are together necessary and sufficient to pattern the helical shape of H. pylori cells After identifying that CcmA was composed of an N-terminal region that may contain a membrane binding motif, a bactofilin domain, and a C-terminal region, we wanted to identify how each region of CcmA contributed to patterning the helical shape of H. pylori cells. The bactofilin literature suggested that the terminal regions on either end of the bactofilin domain may be involved in binding to membranes, modulating protein–protein interactions, or modulating polymerization (Deng et al., 2019; Kühn et al., 2010; Vasa et al., 2015), and we hypothesized deleting the terminal regions of ccmA would alter cell shape. Thus, we generated H. pylori strains that have truncated versions of ccmA at the native ccmA locus. We generated five strains, one strain missing the N-terminal region (∆NT, missing amino acids 2–17), another strain missing the proposed membrane binding motif within the N-terminus (∆MM, missing amino acids 3–12), a third strain lacking the five amino acids at the end of the N-terminus (∆13–17, lacking amino acids 13–17), a fourth strain missing the C-terminal region (∆CT, missing amino acids 119–136), and lastly, a strain expressing only the bactofilin domain that lacks both the N-terminal region and C-terminal region (BD, expressing amino acids 18–118) (Figure 2A). The open-reading frames (ORFs) of the end of csd1 and the beginning of ccmA overlap by 82 nucleotides (Sycuro et al., 2010), thus to avoid impacting the function of Csd1 by removing several amino acids from the C-terminus when truncating the N-terminus of CcmA, we expressed a second copy of csd1 at rdxA, a locus commonly used for complementation (Smeets et al., 2000). In previous work, we confirmed that both ccmA and csd1 can be individually deleted and complemented back without impacting the expression of the other (Sycuro et al., 2010; Yang et al., 2019). Figure 2 with 2 supplements see all Download asset Open asset H. pylori cells expressing CcmA truncation mutants have different cell shapes. (A) Schematic of CcmA and truncation mutants. The N-terminal region (NT, green), bactofilin domain (BD, cyan), and C-terminal region (CT, pink) are indicated, as well as the putative membrane binding motif (MM). (B) Western blot to detect CcmA in whole-cell lysates of H. pylori strains expressing truncated versions of CcmA probed with ɑ-CcmA polyclonal antibody, and ɑ-Cag3 polyclonal antibody as a loading control. (C) Phase-contrast images of H. pylori strains expressing truncated versions of CcmA diagramed in panel (A), scale bars = 1 µm. (D) Histogram displaying the side curvature of H. pylori strains expressing truncated versions of CcmA (WT n = 476 cells, ∆ccmA n = 397 cells, ∆N n = 275 cells, ∆MM n = 391 cells, ∆13–17 n = 361 cells, ∆CT n = 263 cells, BD n = 315 cells). Data are representative of two independent biological replicates. Strains used: SSH51A, SSH53A, SSH55A, SSH54A, SSH67A, SSH56B, and SSH57A. Figure 2—source data 1 Raw, unedited Western blots probed with ɑ-Cag3 and ɑ-CcmA antibodies in whole-cell lysates of H. pylori strains expressing truncated versions of CcmA. https://cdn.elifesciences.org/articles/80111/elife-80111-fig2-data1-v2.zip Download elife-80111-fig2-data1-v2.zip All strains expressed the truncated versions of CcmA measured by Western blotting with an ɑ-CcmA polyclonal antibody; however, in strains lacking the C-terminus (∆CT and BD), we saw much lower signal on the blot (Figure 2B). In follow-up experiments, we determined that the ɑ-CcmA polyclonal antibody fails to recognize versions of CcmA lacking the C-terminus (Figure 2—figure supplement 1). We ran a Western blot probed with our polyclonal ɑ-CcmA antibody on purified 6-His WT CcmA and CcmA truncation mutants (Figure 2—figure supplement 2). Although equal concentrations of each purified protein were loaded, the polyclonal ɑ-CcmA antibody poorly recognized versions of CcmA lacking the C-terminal region (∆CT and BD), suggesting that the ∆CT and BD proteins are likely expressed in H. pylori cells at similar levels to other versions of CcmA but are not robustly recognized by the ɑ-CcmA polyclonal antibody. Next, after confirming that all truncated versions of CcmA were expressed, we assessed the shapes of the cells and found that strains lacking the N-terminal region (∆NT and BD) were indistinguishable from ∆ccmA cells (Figure 2C and D), while cells lacking the C-terminal region of ccmA resembled WT cells. Cells that lacked either the putative membrane binding motif (∆MM) or the last five amino acids of the N-terminal region (∆13–17) were helical but had slightly different side curvature values than the WT population, suggesting that the N-terminal region of CcmA may have multiple functional regions within it. Circular dichroism spectroscopy reveals that CcmA truncation mutants maintain β-strand secondary structure Considering the result that H. pylori strains lacking the N-terminal region of CcmA, cells resembled ∆ccmA mutants, we were curious whether loss of the terminal regions of CcmA might destabilize the protein and/or influence formation of the predicted β-strands (Figure 1). Circular dichroism (CD) spectroscopy can be used to identify the secondary structure and folding of proteins. Different structural elements have characteristic CD spectra, and proteins that consist of β-strands have negative peaks at 216 nm (Greenfield, 2006). We recombinantly expressed and purified 6-his CcmA (Figure 2—figure supplement 2) and collected CD spectra from 200 to 260 nm at fixed temperatures to identify the secondary structure and measure its thermal stability. CD spectra of WT CcmA and the truncation mutants ∆NT, ∆CT, and BD at 20°C all look very similar; they have the characteristic negative peak at 216 nm, indicating β-strand secondary structure (Figure 3A). Together, these data, combined with the modeling by RoseTTAFold in Figure 1C, suggest that CcmA’s bactofilin domain very likely forms a β-helix and confirms that neither terminal region is required for the bactofilin domain to fold properly. In contrast, we also ran CD scans on WT CcmA at 95°C and two CcmA point mutants we have previously shown were unable able to rescue the CcmA null cell shape defect, indicating that they were nonfunctional (Taylor et al., 2020) at 20°C. The CD spectra of both mutants (I55A and L110S) at 20°C resemble spectra of melted WT CcmA at 95°C (Figure 3B), suggesting that these proteins are not folded. Thus, while CcmA ∆NT, BD, I55A, and L110S all have the same cell shape phenotype when expressed in H. pylori – loss of helical cell shape – the mechanism differs. In CcmA I55A and L110S, CcmA is not folded and nonfunctional, while in CcmA ∆NT and BD, the protein is folded, but loss of the N-terminus causes a loss of helical cell shape. Figure 3 Download asset Open asset Circular dichroism spectra of purified 6-his CcmA suggests CcmA is composed of predominantly β-sheets. (A) Circular dichroism spectra of WT and truncated versions of CcmA at room temperature (20°C), WT (black), ∆NT (green), ∆CT (pink), and BD (cyan). (B) Circular dichroism spectra of WT CcmA at room temperature (20°C, black), melted (95°C, dotted line), and two point mutants (I55A, red, and L110S, burgundy). The bactofilin domain alone is capable of polymerization: the terminal regions of CcmA modulate lateral interactions between CcmA filaments Given that terminal region truncation mutant proteins appeared stable and displayed CD spectra indicative of a beta helical structure, we wondered whether their cell shape phenotypes correlated with altered polymerization properties. We assessed polymerization by negative stain and transmission electron microscopy (TEM) of purified truncated versions of CcmA and compared those to full-length protein. As previously reported (Holtrup et al., 2019; Taylor et al., 2020), WT CcmA polymerizes into small filaments that measure on average 3.04 nm (SD = 0.79, n = 18) in width. The filaments wrap together to form bundles of approximately 21.34 nm (SD = 4.82, n = 24) wide, and form lattice structures (Figure 4A and G). ∆NT formed filaments and bundles that were more homogenous, straighter, and thinner than WT and appear to only contain 2–4 filaments each. ∆NT failed to form lattice structures (Figure 4B). ∆MM resembled WT CcmA, forming filaments and bundles of approximately the same width as WT and formed lattices (Figure 4C and G). ∆13–17 resembled ∆NT (Figure 4D and G), suggesting that amino acids 13–17 are responsible for filament bundling properties of ∆NT. ∆CT formed bundles that were wider than WT CcmA but failed to form lattices (Figure 4E and G). Lastly, BD formed straight bundles that were narrower than those found in WT samples and failed to form lattices (Figure 4F and G). These data suggest that the bactofilin domain is sufficient for polymerization of CcmA while the N- and C-terminal regions of CcmA regulate interpolymer interactions that impact the width of bundles by modulating the number of filaments that form a bundle, and the ability of CcmA to form lattices. Taken together with our experiments from Figure 2, where we expressed the truncated versions of CcmA in H. pylori, these data suggest that the ability of CcmA to polymerize is not sufficient to pattern the helical shape of H. pylori cells and in vitro lattice formation does not correlate with helical cell shape. Figure 4 Download asset Open asset The bactofilin domain of CcmA is sufficient for in vitro polymerization while the terminal regions promote lateral polymer interactions. (A–F) Transmission electron microscopy (TEM) of negative stained, purified CcmA, scale bars = 500 nm. White boxes indicate region of micrograph that is enlarged in panel to the right of original. White arrows indicate bundles of CcmA, black arrows indicate lattice structures, and red arrow indicates two bundles wrapping around each other. Data are representative of two independent biological replicates. (G) Box and whiskers plot displaying width of purified CcmA bundles and filaments. Median, min, max, 25th percentile, and 75th percentile are displayed. One-way ANOVA, Dunnett’s multiple-comparison test. ns p>0.5, ***p≤0.001, ****p≤0.0001. WT n = 24, ∆NT n = 29, ∆MM n = 25, ∆13–17 n = 31, ∆CT n = 24, BD n = 32. CcmA’s bactofilin domain mediates interactions with Csd5 and Csd7, and the N-terminal region of CcmA inhibits interactions with Csd7 Given that the truncated versions of CcmA were folded properly and were capable of polymerization in vitro, we hypothesized that the loss of helical cell shape phenotypes we observed when we deleted the N-terminal region of CcmA in Figure 2 could be caused by disrupting interactions between CcmA and other cell-shape-determining proteins. CcmA was previously shown to interact with two Csd proteins, Csd5 and Csd7, by co-immunoprecipitation experiments. Csd5-CcmA interactions were readily detected by co-immunoprecipitation followed by mass spectrometry and Western blotting. However, Csd7-CcmA interactions could only be detected when a cross-linking reagent was included in co-immunoprecipitation experiments and mass spectrometry was used to detect CcmA, suggesting that Csd7-CcmA interactions are weak or potentially transient (Blair et al., 2018; Yang et al., 2019). Interactions between Csd5 and Csd7 were never detected by co-immunoprecipitation experiments followed by mass spectrometry in a WT or ∆ccmA background (Blair, 2018; Blair et al., 2018; Yang et al., 2019). To probe how each region of CcmA contributes to interactions with Csd5 and Csd7, we performed co-immunoprecipitation experiments followed by Western blotting on strains expressing truncated versions of CcmA. Strains were generated that expressed truncated versions of ccmA at the native ccmA locus, csd1 at the rdxA locus as described earlier, and either csd5-2X-FLAG or csd7-3X-FLAG at their native loci. We immunoprecipitated either Csd5-FLAG or Csd7-FLAG with ɑ-FLAG agarose beads, then performed Western blotting and probed with the ɑ-CcmA polyclonal antibody to identify whether the truncated versions of CcmA could still co-purify. we immunoprecipitated all mutant versions of CcmA were detected by Western blotting of the for the ∆CT mutant (Figure is likely that mutant can still interact with we identified that the C-terminal region of CcmA is required for robust by our ɑ-CcmA polyclonal antibody (Figure 2—figure supplement and the BD mutant interacts with Additionally, we WT CcmA, ∆CT, and BD with a in H. pylori at the native ccmA locus and performed a co-immunoprecipitation to detect interactions with Csd5-FLAG (Figure supplement 1). We found that both and were expressed at levels as and could be by These of evidence us to that the ∆CT mutant can interact with suggesting that only the bactofilin domain is required for interactions between CcmA and Figure 5 with 1 supplement see all Download asset Open asset The bactofilin domain interacts with Csd5 and Csd7, and the N-terminal region inhibits Csd7 binding to CcmA. experiments to probe interactions (A) and interactions (B) in H. pylori cells are of Western blot probed with ɑ-CcmA polyclonal antibody of Western blot probed with ɑ-FLAG antibody of Western blot probed with ɑ-CcmA polyclonal antibody of (C) experiments to probe interactions with CcmA and Csd5 in H. pylori strains with and without CcmA. of Western blot probed with polyclonal antibody of to detect the SH3 domain of Western blot probed with ɑ-CcmA polyclonal antibody of Western blot probed with ɑ-FLAG antibody of to detect Western blot probed with polyclonal antibody to detect the SH3 domain of Csd5 in Western blot probed with ɑ-CcmA polyclonal antibody of Data shown are representative of data from independent biological replicates. Strains used: and Figure data 1 Raw, unedited Western blots probed with ɑ-CcmA and ɑ-FLAG antibodies to detect CcmA and Csd5-FLAG or Csd7-FLAG in co-immunoprecipitation experiments. Download we immunoprecipitated we found as previously reported (Yang et al., 2019), WT CcmA was not able to be detected in the by Western blotting background However, versions of CcmA lacking the N-terminal region were robustly by Csd7 (Figure suggesting that the N-terminal region inhibits WT CcmA from by To identify whether deletion of the N-terminus of CcmA caused CcmA, Csd7, and Csd5 to we Csd7-FLAG co-immunoprecipitation experiments in strains expressing WT CcmA, a strain lacking CcmA, and strains expressing CcmA ∆NT or CcmA BD, and probed for interactions with Csd5 by using a polyclonal antibody that the SH3 domain of Csd5 (Blair et al., 2018). We found that in all the we Csd5 never with Csd7 (Figure Together, these data suggest that the bactofilin domain of CcmA mediates interaction with Csd5 and Csd7, the N-terminal region of CcmA inhibits interaction with Csd7, and CcmA forms separate complexes with Csd5 and Csd7. data also that versions of CcmA lacking the C-terminal region are expressed at levels to WT CcmA, they are not recognized as robustly by the ɑ-CcmA polyclonal antibody. CcmA-Csd7 interactions interactions, in Csd1 protein levels After that the N-terminal region of CcmA could interactions with Csd7 and that ∆NT CcmA was readily by Csd7, we that ∆NT CcmA could be binding to Csd7 and its to Csd1, levels of Csd1 protein. This was by the that and ∆NT cells all the same shape phenotype (Figure Yang et al., 2019). To we Csd1 expression by Western blotting and with an polyclonal antibody in whole-cell lysates of the H. pylori strain lacking the N-terminal region of As strain two of is an copy of csd1 at rdxA that was to for potentially impacting function when truncating ccmA of the end of csd1 and the beginning of ccmA overlap by 82 As we found that in the strain lacking the N-terminal region Csd1 levels are lower than in a strain expressing WT CcmA (Figure and Figure Download asset Open asset Csd1 expression is when the N-terminal region of CcmA is deleted to increased Csd7-CcmA interactions that interactions. (A) Western blot of whole-cell probed with polyclonal antibody levels of ɑ-Cag3 polyclonal antibody was used as a loading control. Strains with indicate an copy of csd1 was at the rdxA locus. Data shown are representative of data from independent biological replicates. (B) of Csd1 levels in the ccmA ∆NT strain to the WT signal was by Csd1 signal by signal for each then the data was by by the value from the WT strain from the same Data are from independent biological replicates. (C) experiments to probe Csd1 levels in to interactions in H. pylori cells are Western blot of probed with ɑ-Cag3 polyclonal antibody as loading control. Western blot of probed with polyclonal antibody. Western blot of probed with ɑ-CcmA polyclonal antibody. Western blot probed with ɑ-FLAG antibody of to detect Western blot probed with polyclonal antibody of Western blot probed with ɑ-CcmA polyclonal antibody of Data shown are representative of data from two independent biological replicates. Strains used: SSH51A, SSH53A, SSH55A, and Figure data 1 Raw, unedited Western blots probed with ɑ-Cag3 and antibodies in whole-cell lysates of H. pylori strains expressing truncated versions of CcmA. In unedited Western blots probed with ɑ-CcmA and ɑ-Cag3 and antibodies to detect CcmA, Csd1, and Csd7-FLAG in co-immunoprecipitation experiments. Download After identifying that Csd1 levels were when the N-terminal region of CcmA was we sought to identify whether interactions were when Csd7-CcmA interactions We performed Western blotting and probed for Csd1 levels in the samples we collected during our Csd7-FLAG co-immunoprecipitation experiments (Figure We found that in H. pylori strains lacking the N-terminal region of CcmA, interactions are in to when WT CcmA is expressed (Figure suggesting that when the N-terminal region of CcmA is deleted CcmA-Csd7 interactions and Csd7 from Csd1, Csd1 data suggests that Csd1 stability is indirectly by CcmA Csd7. CcmA binding partners for localization to the major helical axis It has been hypothesized that bactofilins are able to
Source: eLife
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: gold
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