Characterization of the rplB gene from Streptomyces collinus and its protein product by mass spectrometry

Ribosomal protein L2 is the largest protein components of 50S subunits. The protein is implicated in peptidyl transferase activity and binds to functi onally important domains of 23S rRNA. The rplB gene, which codes for riboso mal protein L2 was cloned from Streptomyces collinus. The gene rplB was iso lated from BamHI fragment (3.0 kb) of chromosomal DNA possessing two partia l and four complete ORF's in the order from 5 ' to 3 ': rplC, rplD, rplW, r plB, rpsS, and rplV. The gene organization corresponds to the SIO operon. G ene rplB (834 bp) encodes a polypeptide chain of 278 amino acids. The molec ular mass calculated from genomic structure is 30.5 kDa and pI 11.87. Prote in L2 is rich in positively charged amino acids (Arg 36, Lys 20, and His 11 ). N-terminal domain possesses topology similar to the oligonucleotide/olig osaccharide binding OB folds. The availability of genome sequence makes it possible to identify L2 protein by mass spectrometry, moreover it facilitat es the characterization of its potential posttranslational modifications. T o confirm the protein sequence derived from the rplB gene the tryptic pepti des of L2 were analyzed by mass spectrometric techniques. The obtained data matched exactly with the results of DNA sequencing. (C) 2001 Academic Pres s.