Understanding the role of histidine in the GHSxG acyltransferase active site motif: Evidence for histidine stabilization of the malonyl-enzyme intermediate
- Univ. of California, Berkeley, CA (United States)
- Joint BioEnergy Institute, Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Synthetic Biology Engineering Research Center, Emeryville, CA (United States); Joint BioEnergy Institute, Emeryville, CA (United States)
- Univ. of California, Berkeley, CA (United States); Synthetic Biology Engineering Research Center, Emeryville, CA (United States); Joint BioEnergy Institute, Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Acyltransferases determine which extender units are incorporated into polyketide and fatty acid products. Thus, the ping-pong acyltransferase mechanism utilizes a serine in a conserved GHSxG motif. However, the role of the conserved histidine in this motif is poorly understood. We observed that a histidine to alanine mutation (H640A) in the GHSxG motif of the malonyl-CoA specific yersiniabactin acyltransferase results in an approximately seven-fold higher hydrolysis rate over the wildtype enzyme, while retaining transacylation activity. We propose two possibilities for the reduction in hydrolysis rate: either H640 structurally stabilizes the protein by hydrogen bonding with a conserved asparagine in the ferredoxin-like subdomain of the protein, or a water-mediated hydrogen bond between H640 and the malonyl moiety stabilizes the malonyl-O-AT ester intermediate.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Advanced Research Projects Agency - Energy (ARPA-E); USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- 0000206-1577; AC02-05CH11231
- OSTI ID:
- 1211510
- Journal Information:
- PLoS ONE, Vol. 9, Issue 10; ISSN 1932-6203
- Publisher:
- Public Library of ScienceCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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