HISTONE-LIKE PROTEIN OF STREPTOMYCES-LIVIDANS

A DNA-binding protein (about 10 kDa and pI > 9.7) of Streptomyces livi dans TK24 was purified on a denatured DNA-Cellulose column. and then o n a native DNA-Cellulose column. The N-terminal amino acid sequence of this protein had high homology with those of small basic DNA-binding proteins known as histone-like proteins. Thus, this protein was design ated HS1 (histone-like protein of S. lividans). Gel retardation assay revealed that HS1 bound with the single-stranded DNA as replication in termediates of pSA1.1. We propose that HS1 may participated in the rep lication of pSA1.1. The hup gene encoding HS1 was cloned and sequenced . The deduced N-terminal amino acid sequence, molecular mass (9851 Da) and pI (9.95) were in good agreement with characteristics of HS1. HS1 had the signature sequence for the histone-like proteins. Phylogeneti c analysis suggested that HS1 did not belong to the cluster of histone -like proteins from most of bacteria. The hup transcript of about 500 nucleotides was detected. The hup fragment hybridized with the AseI fr agment C in the 9-10 o'clock region of the chromosome. Total DNAs of m any Streptomyces species hybridized with the internal region of hup.