Histones and nucleoid-associated proteins in Methanosarcina acetivorans mediate recovery from stress and stasis
Year: 2026
Type: article
Abstract: ABSTRACT Many archaea encode histones in tandem with n ucleoid- a ssociated p roteins (NAPs), but the functional overlap between these two classes of non-specific D NA- b inding p roteins (DBPs) is not well studied. Most in vivo studies of DBPs have been conducted with archaea that only encode histones or NAPs. Here, we characterize the endogenous function of the two families of DBPs in a methanogen, Methanosarcina acetivorans , that encodes a histone and two copies of an archaea-specific NAP called m ethanogen c hromatin Protein 1 (MC1). In M. acetivorans, we found that each DBP is individually dispensable, but at least one copy of mc1 appears to be essential. By and large, the single- and double-DBP knockouts phenocopy the wild-type strain under optimal laboratory growth conditions. Remarkably, mutants lacking the histone, one copy of MC1, or both recover faster than wild-type after being subjected to UV shock or long periods of growth stasis. Overexpression of the DBPs leads to a delay in growth recovery after extended periods in stationary phase, which is abrogated by introducing point mutations in DNA-binding residues. Together, our data suggest that histones and MC1 proteins have partially overlapping roles in M. acetivorans , one of which might be genome maintenance when growth has stalled or stopped. IMPORTANCE Though it is known that many archaea encode histones in tandem with archaea-specific n ucleoid- a ssociated p roteins (NAPs), the interplay between these two classes of D NA- b inding p roteins (DBPs) in vivo is not known. Most studies on archaeal DBPs have focused either on archaea known to form histone-based chromatin or on strains that lack histones and compact their genomes exclusively with archaea-specific NAPs. Our study, therefore, fills an important gap in the literature by characterizing DBPs in a model methanogen, Methanosarcina acetivorans , which encodes both histones and archaea-specific NAPs. While no DBP is essential, at least one copy of MC1 appears to be needed, likely for genome compaction. In addition, mutants lacking DBPs had a growth advantage after being subjected to stressors or long periods of growth stasis, indicating that DBPs likely function in genome maintenance when growth has stalled or stopped.
Source: Microbiology Spectrum
Authors: Alienor S. Baskevitch, Dipti D. Nayak
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,500
OpenAlex ID: W7221834266