PCR cloning, sequence analysis and expression of the cybC genes encoding soluble cytochrome b-562 from Escherichia coli B strain OP7 and K strain NM522.

The cybC genes encoding cytochrome b-562 from B and K strains of Escherichia coli were shown to differ in size following their isolation by in vitro amplification using the polymerase chain reaction. Nucleotide sequencing of the genes and flanking regions revealed the discrepancy was due to a 26 bp deletion at the 5' end of the K strain sequence that included the initiation codon. Expression studies confirmed that the K strain gene was untranslated. These data indicate that the cybC gene product is non-essential in E. coli.