| The genome sequence of Escherichia coli has been subjected to intense bioinformatic scrutiny since its release in 1997, allowing relatively facile categorization of the products of its open reading frames (ORFs). It has since become clear through the analysis of genomic and proteomic data that many of these ORFs and the operons of which they are part are either cryptic or expressed to very low levels under growth conditions typically used in the laboratory environment. This raises the possibility that the range of potentially biotechnologically relevant reactions catalyzed by E. coli may be much broader than previously anticipated. We are studying and range of uncharacterized E. coli operons with the aim of determining the structures and functions of their gene products. One example is the yedYZ operon which encodes a two subunit putative oxidoreductase with a soluble molybdenum cofactor-containing catalytic subunit (YedY), and a heme-containing membrane-intrinsic subunit (YedZ). Unprocessed YedY has a twin-arginine leader sequence at its N-terminus, suggesting that it is translocated to the periplasmic compartment by the tat translocon. YedY has significant sequence similarity to a well characterized class of molybdoenzyme which includes plant nitrate reductase and sulfite oxidase from bacteria and mitochondria. |
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