Disease relevance of rpoZ

• To identify the physiological role of the omega subunit, we compared the gene expression profile of wild-type Escherichia coli with that of an rpoZ deleted strain by microarray analysis using an E. coli DNA chip [1].
• It has recently been shown in Mycobacterium smegmatis, by creating a deletion mutation of the rpoZ gene encoding omega, that the physiological role of the omega subunit also includes providing physical protection to beta'. Interestingly, the mutant had altered colony morphology [2].

High impact information on rpoZ

• Previously identified genes in the spo operon were spoS, alias rpoZ, encoding the omega (omega) subunit of RNA polymerase, as well as the spoT gene encoding the major cellular source of guanosine 3',5'-bispyrophosphate hydrolase activity [3].
• This conclusion predicts that a deletion of the omega gene (designated rpoZ or spoS) should show a relaxed RNA control phenotype in vivo [4].
• We determined that the slow-growth phenotype of the insertion mutant is suppressed in relA mutants and that the rpoZ insertion results in a classical SpoT- phenotype [5].
• We constructed an rpoZ insertion mutation by placing a kanamycin resistance cassette into the coding region of the rpoZ gene [5].
• Complementation of the mutant strain with a copy of the wild-type rpoZ gene integrated in the bacterial chromosome restored both sliding motility and biofilm formation to the wild-type state, unequivocally proving the role of omega in the characteristics observed for the mutant bacterium [2].

Biological context of rpoZ

• We mapped the position of rpoZ on the E. coli chromosome by genetic techniques and by examining the restriction map of the whole chromosome and found that rpoZ maps around 82 min, very close to spoT [5].

References