Light-inducible carotenoid production controlled by a MarR-type regulator in Corynebacterium glutamicum

Sci Rep. 2019 Sep 11;9(1):13136. doi: 10.1038/s41598-019-49384-7.

Abstract

Carotenoid production in some non-phototropic bacteria occurs in a light-dependent manner to protect cells from photo-oxidants. Knowledge regarding the transcriptional regulator involved in the light-dependent production of carotenoids of non-phototrophic bacteria has been mainly confined to coenzyme B12-based photo-sensitive regulator CarH/LitR family proteins belonging to a MerR family transcriptional regulator. In this study, we found that bacteria belonging to Micrococcales and Corynebacteriales exhibit light-dependent carotenoid-like pigment production including an amino acid-producer Corynebacterium glutamicum AJ1511. CrtR is a putative MarR family transcriptional regulator located in the divergent region of a carotenoid biosynthesis gene cluster in the genome of those bacteria. A null mutant for crtR of C. glutamicum AJ1511 exhibited constitutive production of carotenoids independent of light. A complemented strain of the crtR mutant produced carotenoids in a light-dependent manner. Transcriptional analysis revealed that the expression of carotenoid biosynthesis genes is regulated in a light-dependent manner in the wild type, while the transcription was upregulated in the crtR mutant irrespective of light. In vitro experiments demonstrated that a recombinant CrtR protein binds to the specific sequences within the intergenic region of crtR and crtE, which corresponds to -58 to -7 for crtE, and +26 to -28 for crtR with respect to the transcriptional start site, and serves as a repressor for crtE transcription directed by RNA polymerase containing SigA. Taken together, the results indicate that CrtR light-dependently controls the expression of the carotenoid gene cluster in C. glutamicum and probably closely related Actinobacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Base Sequence
  • Carotenoids / metabolism*
  • Corynebacterium glutamicum / genetics*
  • Corynebacterium glutamicum / metabolism
  • Gene Expression Regulation, Bacterial / radiation effects*
  • Light*
  • Multigene Family / genetics
  • Promoter Regions, Genetic / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription Initiation Site
  • Transcription, Genetic / radiation effects*

Substances

  • Bacterial Proteins
  • Carotenoids