A thylakoid biogenesis BtpA protein is required for the initial step of tetrapyrrole biosynthesis in cyanobacteria

ABSTRACT: Biogenesis of the photosynthetic apparatus requires complicated molecular machinery, individual components of which are either poorly characterized or unknown. The BtpA protein has been described as a factor required for the stability of Photosystem I (PSI) in cyanobacteria; however, how the BtpA stabilized PSI remains unexplained. To clarify the role of BtpA, we constructed and characterized the btpA-null mutant (btpA) in the cyanobacterium Synechocystis sp. PCC 6803. The mutant contained only ~ 1% of chlorophyll and nearly no thylakoid membranes. However, this strain, growing only in the presence of glucose, was genetically unstable and readily generate suppressor mutations that restore the photoautotrophy. Two suppressor mutations were mapped into the hemA gene encoding glutamyl-tRNA reductase (GluTR) - the first enzyme of tetrapyrrole biosynthesis. Indeed, the GluTR was not detectable in the btpA mutant and the suppressor mutations restored biosynthesis of tetrapyrroles and photoautotrophy by increased GluTR expression or by improved GluTR stability/processivity. We further demonstrated that GluTR associates with a large BtpA oligomer and that BtpA is required for the stability of GluTR. Our results show that the BtpA protein is involved in the biogenesis of photosystems on the level of regulation of tetrapyrrole biosynthesis.

INSTRUMENT(S): timsTOF Pro

ORGANISM(S): Synechocystis Sp. Pcc 6803 (ncbitaxon:1148)

SUBMITTER: Roman Sobotka  

PROVIDER: MSV000092431 | MassIVE | Thu Jul 13 07:24:00 BST 2023

SECONDARY ACCESSION(S): PXD043762

REPOSITORIES: MassIVE