The Acetyltransferase RibT From Bacillus subtilis Affects in vivo Dynamics of the Multimeric Heavy Riboflavin Synthase Complex
Flavins are ubiquitous molecules in life as they serve as important enzyme cofactors. In the Gram-positive, soil-dwelling bacterium Bacillus subtilis, four well-characterized gene products (the enzymes RibDG, RibE, RibAB, and RibH) catalyze the biosynthesis of riboflavin (RF) from guanosine-triph...
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|Summary:||Flavins are ubiquitous molecules in life as they serve as important enzyme cofactors.
In the Gram-positive, soil-dwelling bacterium Bacillus subtilis, four well-characterized
gene products (the enzymes RibDG, RibE, RibAB, and RibH) catalyze the biosynthesis
of riboflavin (RF) from guanosine-triphosphate (GTP) and ribulose-5-phosphate (R5P).
The corresponding genes form an operon together with the gene ribT (ribDG-E-AB-H-T),
wherein the function of this terminal gene remained enigmatic. RibT has been structurally
characterized as a GCN5-like acetyltransferase (GNAT), however, with unidentified target
molecules. Bacterial two-hybrid system revealed interactions between RibT, RibH, and
RibE, forming the heavy RF synthase complex. Applying single particle tracking (SPT), we
found that confined (sub)diffusion of RibT is largely dependent on interacting RibE and, to
a lesser degree, on interacting RibH. By induced expression of otherwise low-expressed
ribT from an ectopic locus, we observed a decrease in the subpopulation considered
to represent capsids of the heavy RF synthase and an increase in the subpopulation
thought to represent pentamers of RibH, pointing to a putative role for RibT in capsid
disassembly. Complementarily, either deletion of ribT or mutation of a key residue from
RibH (K29) suspected to be the substrate of RibT for acetylation leads to increased levels
of subpopulations considered as capsids of RibH-mVenus (RibH-mV) in comparison to
wild-type (wt)-like cells. Thus, we provide evidence for an indirect involvement of RibT in
RF biosynthesis by a putative capsid disassembling mechanism considered to involve
acetylation of RibH residue K29 at the three-fold symmetry axis of 60-mer capsids.|
|Item Description:||Gefördert durch den Open-Access-Publikationsfonds der UB Marburg.|
|Physical Description:||19 Pages|