THE CYDD GENE-PRODUCT, COMPONENT OF A HETERODIMERIC ABC TRANSPORTER, IS REQUIRED FOR ASSEMBLY OF PERIPLASMIC CYTOCHROME-C AND OF CYTOCHROME-BD IN ESCHERICHIA-COLI
Rk. Poole et al., THE CYDD GENE-PRODUCT, COMPONENT OF A HETERODIMERIC ABC TRANSPORTER, IS REQUIRED FOR ASSEMBLY OF PERIPLASMIC CYTOCHROME-C AND OF CYTOCHROME-BD IN ESCHERICHIA-COLI, FEMS microbiology letters, 117(2), 1994, pp. 217-224
The cydD gene of Escherichia coli encodes a protein which, together wi
th the CydC protein, probably constitutes a heterodimeric, ABC-family
membrane transporter, necessary for biosynthesis of the cytochrome bd
quinol oxidase. Here, we demonstrate that a cydD mutant also fails to
synthesise periplasmic c-type cytochrome(s), suggesting that the trans
porter exports haem or some other component involved in assembly of cy
tochromes that are found in, or exposed to, the periplasm. The CydDC s
ystem appears to be the first example of a transporter required for pe
riplasmic cytochrome assembly processes requiring more than one type o
f haem. A mutant defective in trxB (adjacent to the cydDC operon, and
encoding thioredoxin reductase) was unaffected in cytochrome c or bd a
ssembly.