Faculty Opinions recommendation of Ligand specificity of group I biotin protein ligase of Mycobacterium tuberculosis.
Year: 2008
Type: peer-review
Abstract: Background: Fatty acids are indispensable constituents of mycolic acids that impart toughness & permeability barrier to the cell envelope of M. tuberculosis.Biotin is an essential co-factor for acetyl-CoA carboxylase (ACC) the enzyme involved in the synthesis of malonyl-CoA, a committed precursor, needed for fatty acid synthesis.Biotin carboxyl carrier protein (BCCP) provides the co-factor for catalytic activity of ACC.Methodology/Principal Findings: BPL/BirA (Biotin Protein Ligase), and its substrate, biotin carboxyl carrier protein (BCCP) of Mycobacterium tuberculosis (Mt) were cloned and expressed in E. coli BL21.In contrast to EcBirA and PhBPL, the ,29.5 kDa MtBPL exists as a monomer in native, biotin and bio-59AMP liganded forms.This was confirmed by molecular weight profiling by gel filtration on Superdex S-200 and Dynamic Light Scattering (DLS).Computational docking of biotin and bio-59AMP to MtBPL show that adenylation alters the contact residues for biotin.MtBPL forms 11 H-bonds with biotin, relative to 35 with bio-59AMP.Docking simulations also suggest that bio-59AMP hydrogen bonds to the conserved 'GRGRRG' sequence but not biotin.The enzyme catalyzed transfer of biotin to BCCP was confirmed by incorporation of radioactive biotin and by Avidin blot.The K m for BCCP was ,5.2 mM and ,420 nM for biotin.MtBPL has low affinity (K b = 1.06610 26 M) for biotin relative to EcBirA but their K m are almost comparable suggesting that while the major function of MtBPL is biotinylation of BCCP, tight binding of biotin/bio-59AMP by EcBirA is channeled for its repressor activity. Conclusions/Significance:These studies thus open up avenues for understanding the unique features of MtBPL and the role it plays in biotin utilization in M. tuberculosis.
Author: Niyaz Ahmed
Institution: International Centre for Diarrhoeal Disease Research
Language: English
Topic: Biotin and Related Studies
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W4205386879