-
[show abstract]
[hide abstract]
ABSTRACT: The bacterial acquired immune system consists of clustered regularly interspaced short palindromic repeats (CRISPRs) and CRIPSR-associated (Cas) genes, which include Cas-module repeat-associated mysterious proteins (Cmr). The six Cmr proteins of Pyrococcus furiosus (pfCmr1-pfCmr6) form a Cmr effector complex that functions against exogenous nucleic acid. Among the Cmr proteins, the role of pfCmr5 and its involvement in the complex's cleavage activity have been obscure. The elucidated pfCmr5 structure has two inserted α-helices compared with the other trimeric Cmr5 structure. However, pfCmr5 exists as a monomeric protein both in the crystalline state and in solution. In vitro assays indicate that pfCmr5 interacts with pfCmr4. These structural and biophysical data might help in understanding the complicated and ill-characterized Cmr effector complex. STRUCTURED SUMMARY OF PROTEIN INTERACTIONS: pfCmr4 and pfCmr5 bind by molecular sieving (View interaction)pfCmr4 and pfCmr4 bind by molecular sieving (View interaction)pfCmr5 and pfCmr4 bind by ion exchange chromatography (View interaction).
FEBS letters 01/2013; · 3.54 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In multifunctional type I restriction enzymes, active methyltransferases (MTases) are constituted of methylation (HsdM) and specificity (HsdS) subunits. In this study, the crystal structure of a putative HsdM subunit from Vibrio vulnificus YJ016 (vvHsdM) was elucidated at a resolution of 1.80 Å. A cofactor-binding site for S-adenosyl-L-methionine (SAM, a methyl-group donor) is formed within the C-terminal domain of an α/β-fold, in which a number of residues are conserved, including the GxGG and (N/D)PP(F/Y) motifs, which are likely to interact with several functional moieties of the SAM methyl-group donor. Comparison with the N6 DNA MTase of Thermus aquaticus and other HsdM structures suggests that two aromatic rings (Phe199 and Phe312) in the motifs that are conserved among the HsdMs may sandwich both sides of the adenine ring of the recognition sequence so that a conserved Asn residue (Asn309) can interact with the N6 atom of the target adenine base (a methyl-group acceptor) and locate the target adenine base close to the transferred SAM methyl group.
Acta crystallographica. Section D, Biological crystallography 11/2012; 68(Pt 11):1570-7. · 12.67 Impact Factor
-
Proteins Structure Function and Bioinformatics 02/2012; 80(7):1895-900. · 3.39 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The ethanologenic bacterium Zymomonas mobilis ZM4 is of special interest because it has a high ethanol yield. This is made possible by the two alcohol dehydrogenases (ADHs) present in Z. mobilis ZM4 (zmADHs), which shift the equilibrium of the reaction toward the synthesis of ethanol. They are metal-dependent enzymes: zinc for zmADH1 and iron for zmADH2. However, zmADH2 is inactivated by oxygen, thus implicating zmADH2 as the component of the cytosolic respiratory system in Z. mobilis. Here, we show crystal structures of zmADH2 in the form of an apo-enzyme and an NAD+–cofactor complex. The overall folding of the monomeric structure is very similar to those of other functionally related ADHs with structural variations around the probable substrate and NAD+ cofactor binding region. A dimeric structure is formed by the limited interactions between the two subunits with the bound NAD+ at the cleft formed along the domain interface. The catalytic iron ion binds near to the nicotinamide ring of NAD+, which is likely to restrict and locate the ethanol to the active site together with the oxidized Cys residue and several nonpolar bulky residues. The structures of the zmADH2 from the proficient ethanologenic bacterium Z. mobilis, with and without NAD+ cofactor, and modeling ethanol in the active site imply that there is a typical metal-dependent catalytic mechanism.
Journal of Molecular Biology 02/2011; 407(3):413-24. · 4.00 Impact Factor
