Zinc Finger Protein LipR Represses Docosahexaenoic Acid and Lipid Biosynthesis in Schizochytrium sp.

Publisher: American Society for Microbiology Country of Publication: United States NLM ID: 7605801 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1098-5336 (Electronic) Linking ISSN: 00992240 NLM ISO Abbreviation: Appl Environ Microbiol Subsets: MEDLINE

Original Publication: Washington, American Society for Microbiology.

Docosahexaenoic Acids*/metabolism ; Stramenopiles*/genetics ; Stramenopiles*/metabolism; Fatty Acids/metabolism ; Fatty Acids, Unsaturated/metabolism ; Zinc Fingers

The heterotrophic marine microalgae Schizochytrium sp. is an important industrial producer of docosahexaenoic acid (DHA). Increased production of DHA and lipids in Schizochytrium sp. has been achieved by standard fermentation optimization and metabolic engineering methods; however, regulatory mechanisms for DHA and lipid biosynthesis remain unknown. In this study, the C 2 H 2 zinc finger protein LipR was identified in Schizochytrium sp. ATCC 20888 by transcriptional analysis. Deletion of the lipR gene significantly ( P <  0.001) increased production of total lipids and DHA by 33% and 48%, respectively. LipR repressed DHA and lipid production by directly inhibiting transcription of polyunsaturated fatty acid (PUFA) and fatty acid synthase (FAS) genes ( pfa1 , pfa2 , pfa3 , and fas ). Specific binding of LipR to 9-bp recognition sequence 5'-(C/A)(A/G)CCATCTT-3' in upstream regions of target genes was demonstrated by electrophoretic mobility shift assays (EMSAs) and DNase I footprinting assays. Expression of several key genes ( acc , acl , ampD , fabD , mae , zwf , and dga1 ) related to levels of precursors and NADPH, and to triacylglycerol storage rate, were also directly repressed by LipR. Our findings, taken together, indicate that the evolutionarily unique regulator LipR is an essential repressor of DHA and saturated fatty acid biosynthesis in Schizochytrium sp. IMPORTANCE Regulatory mechanisms for DHA and saturated fatty acid biosynthesis in the heterotrophic marine microalgae Schizochytrium sp. are unclear. We demonstrate here that deletion of the gene ( lipR ) encoding the C 2 H 2 zinc finger protein LipR promotes DHA and saturated fatty acid production in this genus. LipR acts as a key repressor of such production by binding to 9-bp consensus sequence 5'-(C/A)(A/G)CCATCTT-3' in the upstream regions of polyunsaturated fatty acid and fatty acid synthase genes ( pfa1 , pfa2 , pfa3 , and fas ), and genes related to levels of precursors and NADPH ( acc , acl , ampD , fabD , mae , and zwf ), and to triacylglycerol storage rate ( dga1 ). This is the first demonstration that a regulator inhibits synthesis of DHA and lipids in Schizochytrium sp. by directly controlling transcription of PUFA synthase and fas genes. Manipulation of the lipR gene provides a potential strategy for enhancing accumulation of polyunsaturated fatty acids and lipids in thraustochytrids.

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Keywords: C2H2 zinc finger protein; LipR; Schizochytrium sp.; docosahexaenoic acid; lipogenesis; polyunsaturated fatty acid synthase

0 (Fatty Acids)
0 (Fatty Acids, Unsaturated)
25167-62-8 (Docosahexaenoic Acids)

Date Created: 20220202 Date Completed: 20220325 Latest Revision: 20220924

20240829

PMC8939356

10.1128/aem.02063-21

35108079