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Main conclusion <p>The multifunctional acyltransferases (MFAT) from <i>Synechocystis sp.</i> PCC 6803 and <i>Synechococcus sp.</i> PCC 7002 synthesize triacylglycerol, fatty acid phytyl esters, acylated plastoquinol-9 and acylated plastoquinone C, while <i>Gloeobacter violaceus</i> PCC 7421 synthesizes acylated plastoquinol-9 in an MFAT-independent pathway.</p> Abstract <p>Cyanobacteria contain large amounts of polar lipids in their thylakoid membranes, but the contents of nonpolar lipids are low. We previously identified triacylglycerol (TAG) and fatty acid phytyl esters (FAPE) in <i>Synechocystis sp.</i> PCC 6803, and described a gene (<i>slr2103</i>) involved in TAG and FAPE synthesis. Other studies showed that <i>Synechocystis sp.</i> PCC 6803 and <i>Synechococcus sp.</i> PCC 7002 synthesizes acylated forms of plastoquinol-9 (acyl-PQH) and of plastoquinone C (acyl-PQC), which carries the fatty acid on a hydroxyl group on the isoprenoid chain, but TAG and FAPE were not detected. We confirm here that <i>Synechocystis sp.</i> PCC 6803 and <i>Synechococcus sp.</i> PCC 7002 contain TAG, FAPE, acyl-PQH and acyl-PQC. Expression of <i>slr2103</i> and the related gene <i>A0918</i> from <i>Synechococcus sp.</i> PCC 7002 in <i>Escherichia coli,</i> and analysis of the respective cyanobacterial mutants revealed that the two proteins acylate diacylglycerol, phytol, and the plastoquinol-9 analog decylplastoquinol. Therefore, <i>slr2103</i> and <i>A0918</i> encode multifunctional acyltransferases (MFAT) with broad substrate specificities. <i>Gloeobacter violaceus</i> PCC 7421, a primitive cyanobacterium that lacks an MFAT-like gene, accumulates acyl-PQH, indicating that this strain harbors an MFAT-independent acyltransferase capable of acylating plastoquinol-9. These results demonstrate that cyanobacteria synthesize different nonpolar lipids including TAG, FAPE and acylated forms of plastoquinol, employing MFAT-dependent and MFAT-independent pathways.</p>

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Multifunctional acyltransferases involved in the synthesis of triacylglycerol, fatty acid phytyl esters and plastoquinol esters in cyanobacteria

  • 期刊论文

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  • 发表日期：

    2025年5月2日

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  • Amita Shajil Das,
  • Arpita Shajil Das,
  • Zishuo Chen,
  • Helga Peisker,
  • Katharina Gutbrod,
  • Georg Hölzl,
  • Peter Dörmann

摘要

Main conclusion

The multifunctional acyltransferases (MFAT) from Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002 synthesize triacylglycerol, fatty acid phytyl esters, acylated plastoquinol-9 and acylated plastoquinone C, while Gloeobacter violaceus PCC 7421 synthesizes acylated plastoquinol-9 in an MFAT-independent pathway.

Abstract

Cyanobacteria contain large amounts of polar lipids in their thylakoid membranes, but the contents of nonpolar lipids are low. We previously identified triacylglycerol (TAG) and fatty acid phytyl esters (FAPE) in Synechocystis sp. PCC 6803, and described a gene (slr2103) involved in TAG and FAPE synthesis. Other studies showed that Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002 synthesizes acylated forms of plastoquinol-9 (acyl-PQH) and of plastoquinone C (acyl-PQC), which carries the fatty acid on a hydroxyl group on the isoprenoid chain, but TAG and FAPE were not detected. We confirm here that Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002 contain TAG, FAPE, acyl-PQH and acyl-PQC. Expression of slr2103 and the related gene A0918 from Synechococcus sp. PCC 7002 in Escherichia coli, and analysis of the respective cyanobacterial mutants revealed that the two proteins acylate diacylglycerol, phytol, and the plastoquinol-9 analog decylplastoquinol. Therefore, slr2103 and A0918 encode multifunctional acyltransferases (MFAT) with broad substrate specificities. Gloeobacter violaceus PCC 7421, a primitive cyanobacterium that lacks an MFAT-like gene, accumulates acyl-PQH, indicating that this strain harbors an MFAT-independent acyltransferase capable of acylating plastoquinol-9. These results demonstrate that cyanobacteria synthesize different nonpolar lipids including TAG, FAPE and acylated forms of plastoquinol, employing MFAT-dependent and MFAT-independent pathways.