Open AccessExpression of the heme biosynthetic pathway genes hemCD , hemH , hemM and hemA of Escherichia coli
Author(s) -
McNicholas Paul M,
Javor George,
Darie Silvia,
Gunsalus Robert P
Publication year - 1997
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1997.tb10184.x
Subject(s) - porphobilinogen deaminase , heme , escherichia coli , operon , ferrochelatase , gene , microbiology and biotechnology , biology , porphobilinogen , lac operon , biochemistry , enzyme , transcription (linguistics) , structural gene , chemistry , linguistics , philosophy
Little is known about the control of latter steps of heme biosynthesis in Escherichia coli . In this study we examined the transcriptional regulation of genes that encode two intermediate heme pathway enzymes, porphobilinogen deaminase ( hemC ) and uroporphyrinogen III cosynthase ( hemD ), and the final enzyme of the pathway, ferrochelatase ( hemH ). We also reexamined the regulation of hemA and the gene located immediately upstream of hemA , hemM . The regulatory regions of hemC , hemH , hemA and hemM were fused to lacZ . The resultant operon fusions were inserted into the E. coli chromosome in single copy and expression monitored under conditions of oxygen and heme limitation. Expression of hemM appeared constitutive under the conditions tested here. In contrast, expression of hemCD , hemH and hemA were shown to be mildly regulated in response to heme availability. Thus, transcription of four of the nine genes of the E. coli heme pathway appears to be only mildly regulated in response to heme limitation.