A novel gene - samfR involved in early stage of Streptomyces ansochromogenes differentiation

A 4.6 kb DNA fragment was cloned from the DNA library of Streptomyces ansoc hromogenes using a partial DNA fragment located in the downstream of promot er-P-TH4 as probe. The experiments revealed that this DNA fragment consists of sawD gene and a 1.4 kb Pvu II fragment which can accelerate mycelium fo rmation of S. ansochromogenes. The nucleotide sequence of 1.4 kb DNA fragme nt was determined and analysed; the result indicated that the fragment cont ains one complete open reading frame (ORF) which encodes a protein with 213 amino acids, and this gene was designated as samfR. The deduced protein ha s 36% amino acid identities and 52% amino acid similarities in comparison w ith that encoded by hppR gene, which is involved in the regulation of catab olism for 3-(3-hydroxyphenyl) propionate (3HPP) in Rhodococcus globerulus. The function of samfR gene was studied using strategy of gene disruption, a nd the resulting samfR mutant failed to form aerial hyphae and spores, its development and differentiation stopped at the stage of substrate mycelium in contrast with wild type strain. The results showed that the samfR gene i s closely related to S. ansochromogenes differentiation.