2WK9

Structure of Plp_Thr aldimine form of Vibrio cholerae CqsA

Summary for 2WK9

• Entry DOI: 10.2210/pdb2wk9/pdb
• Related: 2WK7 2WK8 2WKA
• Descriptor: CAI-1 AUTOINDUCER SYNTHASE, PYRIDOXAL-5'-PHOSPHATE, SULFATE ION, ... (5 entities in total)
• Functional Keywords: oxoamine-synthases, pyridoxal phosphate, cqsa, cai-1, transferase, autoinducer, quorum-sensing, acyltransferase, aminotransferase
• Biological source: VIBRIO CHOLERAE O1 BIOVAR EL TOR
• Total number of polymer chains: 2
• Total formula weight: 88316.63

Authors

Jahan, N.,Potter, J.A.,Sheikh, M.A.,Botting, C.H.,Shirran, S.L.,Westwood, N.J.,Taylor, G.L. (deposition date: 2009-06-08, release date: 2009-07-21, Last modification date: 2024-05-08)

Primary citation

Jahan, N.,Potter, J.A.,Sheikh, M.A.,Botting, C.H.,Shirran, S.L.,Westwood, N.J.,Taylor, G.L.
Insights Into the Biosynthesis of the Vibrio Cholerae Major Autoinducer Cai-1 from the Crystal Structure of the Plp-Dependent Enzyme Cqsa.
J.Mol.Biol., 392:763-, 2009

PubMed Abstract: CqsA is an enzyme involved in the biosynthesis of cholerae autoinducer-1 (CAI-1), the major Vibrio cholerae autoinducer engaged in quorum sensing. The amino acid sequence of CqsA suggests that it belongs to the family of alpha-oxoamine synthases that catalyse the condensation of an amino acid to an acyl-CoA substrate. Here we present the apo- and PLP-bound crystal structures of CqsA and confirm that it shares structural homology with the dimeric alpha-oxoamine synthases, including a conserved PLP-binding site. The chemical structure of CAI-1 suggests that decanoyl-CoA may be one substrate of CqsA and that another substrate may be l-threonine or l-2-aminobutyric acid. A crystal structure of CqsA at 1.9-A resolution obtained in the presence of PLP and l-threonine reveals an external aldimine that has lost the l-threonine side chain. Similarly, a 1.9-A-resolution crystal structure of CqsA in the presence of PLP, l-threonine, and decanoyl-CoA shows a trapped external aldimine intermediate, suggesting that the condensation and decarboxylation steps have occurred, again with loss of the l-threonine side chain. It is suggested that this side-chain loss, an observation supported by mass spectrometry, is due to a retro-aldol reaction. Although no structural data have been obtained on CqsA using l-2-aminobutyric acid and decanoyl-CoA as substrates, mass spectrometry confirms the expected product of the enzyme reaction. It is proposed that a region of structure that is disordered in the apo structure is involved in the release of product. While not confirming if CqsA alone is able to synthesize CAI-1, these results suggest possible synthetic routes.

PubMed: 19631226
DOI: 10.1016/J.JMB.2009.07.042

Experimental method

X-RAY DIFFRACTION (1.9 Å)