Zhu G, Tan W, Xie L, Ma C, Chen X, Zhang S, Wei Y. Mechanisms underlying the inhibitory effects of Cd
2+ on prodigiosin synthesis in Serratia marcescens KMR-3.
J Inorg Biochem 2022;
236:111978. [PMID:
36063739 DOI:
10.1016/j.jinorgbio.2022.111978]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 08/17/2022] [Accepted: 08/20/2022] [Indexed: 12/15/2022]
Abstract
Prodigiosin (2-methyl-3-pentyl-6-methoxyprodiginine), a red-colored microbial pigment, is produced in large quantities by Serratia marcescens KMR-3. This bacterium can grow in a medium with a Cd2+ concentration of 500 mg/L, but it does not produce prodigiosin when the Cd2+ concentration in the medium is higher than 140 mg/L. Therefore, we investigated the mechanisms by which Cd2+ inhibits prodigiosin synthesis. Upon addition of Cd2+ to the medium, the expression of the prodigiosin (pig) gene cluster was significantly downregulated. Simultaneously, genes encoding proteins related to the synthesis of arginine and proline(prodigiosin precursors) were significantly downregulated, while the degradation-related genes were upregulated. Furthermore, PigF, which encodes a key enzyme involved in the synthesis of 4-methoxy-2,2'-bipyrrole-5-carboxaldehyde and PigC, which encodes a key enzyme involved in the last step of prodigiosin synthesis, were downregulated by 80% and 55%, respectively, following Cd2+ treatment. As PigC and PigF are located on the cell membrane and are involved in the final steps of prodigiosin synthesis, the cell membrane might be presumed to be the site of prodigiosin synthesis. The bacterial membrane exhibited different degrees of elongation, folding, fragmentation, and sagging after the addition of Cd2+, while likely destroying the site of prodigiosin synthesis.
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