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The LysR ‐type transcription factor HbrL is a global regulator of iron homeostasis and porphyrin synthesis in R hodobacter capsulatus
Author(s) -
Zappa Sébastien,
Bauer Carl E.
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12431
Subject(s) - biology , rhodobacter , mutant , activator (genetics) , regulator , ferrous , biochemistry , gene , transcription factor , transcriptional regulation , tetrapyrrole , gene expression , microbiology and biotechnology , chemistry , organic chemistry , enzyme
Summary The purple bacterium R hodobacter capsulatus is unique among R hodobacteriacae as it contains a putative i ron r esponse r egulator ( Irr ) but does not possess a copy of the f erric u ptake r egulator ( Fur ). Interestingly, an in‐frame deletion mutant of Irr shows no major role in iron homeostasis. Instead, we showed that the previously identified activator of haem gene expression HbrL is a crucial regulator of iron homeostasis. We demonstrated that an HbrL deletion strain is unable to grow in iron‐limited medium in aerobic, semi‐aerobic and photosynthetic conditions and that suppressor strains can be isolated with mutations in iron uptake genes. Gene expression studies revealed that HbrL is a transcriptional activator of multiple ferrous and ferric iron uptake systems in addition to a haem uptake system. Finally, HbrL activates the expression of numerous haem biosynthesis genes. Thus, HbrL has a central role in controlling the amount of iron transport in conjunction with the synthesis of its cognate tetrapyrrole haem.