HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplementary data Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Saborido Basconcillo, L. Articles by McCarry, B. E. Search for Related Content PubMed PubMed Citation Articles by Saborido Basconcillo, L. Articles by McCarry, B. E. Agricola Articles by Saborido Basconcillo, L. Articles by McCarry, B. E.

Cyclopropane fatty acyl synthase in Sinorhizobium meliloti

¹ Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4L8, Canada
² Center for Environmental Genomics, Department of Biology, McMaster University, Hamilton, Ontario L8S 4L8, Canada

Correspondence
Brian E. McCarry
mccarry{at}mcmaster.ca

Cyclopropane fatty acyl synthases (CFA synthases) are enzymes that catalyse the addition of a methylene group across cis double bonds of monounsaturated fatty acyl chains in lipids. We have investigated the function of two putative genes, cfa1 and cfa2, proposed to code for CFA synthases in Sinorhizobium meliloti. Total fatty acid composition and fatty acid distributions within lipid classes for wild-type and cfa1 and cfa2 mutant strains grown under P_i starvation and in acidic culture conditions were obtained by GC/MS and by infusion ESI/MS/MS, respectively. For wild-type cells and the cfa1 mutant, total cyclopropane fatty acids (CFAs) increased by 10 % and 15 % under P_i starvation and acidic conditions, respectively; whereas in the cfa2 mutant, CFAs were less than 0.1 % of wild-type under both growth conditions. Reporter gene fusion experiments revealed that cfa1 and cfa2 were expressed at similar levels in free-living cells. Thus under the conditions we examined, cfa2 was required for the cyclopropanation of lipids in S. meliloti whereas the role of cfa1 remains to be determined. Analysis of intact lipids revealed that cyclopropanation occurred on cis-11-octadecenoic acid located in either the sn-1 or the sn-2 position in phospholipids and that cyclopropanation in the sn-2 position occurred to a greater extent in phosphatidylcholines and sulfoquinovosyldiacylglycerols under acidic conditions than under P_i starvation. The cfa2 gene was also required for cyclopropanation of non-phosphorus-containing lipids. Principal components analysis revealed no differences in the cyclopropanation of four lipid classes. We concluded that cyclopropanation occurred independently of the polar head group. Neither cfa1 nor cfa2 was required for symbiotic nitrogen fixation.

A supplementary table and figure are available with the online version of this paper.

This article has been cited by other articles:

				L. S. Basconcillo, R. Zaheer, T. M. Finan, and B. E. McCarry A shotgun lipidomics approach in Sinorhizobium meliloti as a tool in functional genomics J. Lipid Res., June 1, 2009; 50(6): 1120 - 1132. [Abstract] [Full Text] [PDF]