Molecular Phylogenetic Characterization of Streptomyces Protease Inhibitor Family

Abstract

We previously found that proteinaceous protease inhibitors homologous to Streptomyces subtilisin inhibitor (SSI) are widely produced by various Streptomyces species, and we designated them "SSI-like proteins" (Taguchi S, Kikuchi H, Suzuki M, Kojima S, Terabe M, Miura K, Nakase T, Momose H [1993] Appl Environ Microbiol 59:4338-4341). In this study, SSI-like proteins from five strains of the genus Streptoverticillium were purified and sequenced, and molecular phylogenetic trees were constructed on the basis of the determined amino acid sequences together with those determined previously for Streptomyces species. The phylogenetic trees showed that SSI-like proteins from Streptoverticillium species are phylogenetically included in Streptomyces SSI-like proteins but form a monophyletic group as a distinct lineage within the Streptomyces proteins. This provides an alternative phylogenetic framework to the previous one based on partial small ribosomal RNA sequences, and it may indicate that the phylogenetic affiliation of the genus Streptoverticillium should be revised. The phylogenetic trees also suggested that SSI-like proteins possessing arginine or methionine at the P1 site, the major reactive center site toward target proteases, arose multiple times on independent lineages from ancestral proteins possessing lysine at the P1 site. Most of the codon changes at the P1 site inferred to have occurred during the evolution of SSI-like proteins are consistent with those inferred from the extremely high G + C content of Streptomyces genomes. The inferred minimum number of amino acid replacements at the P1 site was nearly equal to the average number for all the variable sites. It thus appears that positive Darwinian selection, which has been postulated to account for accelerated rates of amino acid replacement at the major reaction center site of mammalian protease inhibitors, may not have dictated the evolution of the bacterial SSI-like proteins.

Posttranslational processing of the xylanase Xys1L from Streptomyces halstedii JM8 is carried out by secreted serine proteases

“…PMSFinduced inhibition of processing was also observed, again suggesting that extracellular serine proteases were involved (data not shown). Since most members of the genus Streptomyces are a good source of proteinaceous serine protease inhibitors (Taguchi et al, 1993(Taguchi et al, , 1997, we decided to study the effect of the subtilisin-type inhibitor (SLPI) from S. lividans on the processing of Xys1L. First, 20 putative S. lividans SLPIdefective strains were obtained following the method of Taguchi et al (1995a) (see Methods); it was observed that most of them were also subject to growth problems in complex media.…”

“…JM8 shows the processing by the filtered supernatant of the S. halstedii JM8 strain; 3 mg total protein was used. SpB, pure protease from S. lividans; SAM-P20, protease isolated from S. coelicolor Mü ller homologous to SAM-P20 from S. albogriseolus; SAM-P26, protease from S. albogriseolus (Taguchi et al, 1998); SAM-P45, protease from S. albogriseolus (Suzuki et al, 1997).…”

“…Some homologues of these proteases have been cloned from different Streptomyces strains. Among them, SAM-P20 (Taguchi et al, 1995b), SAM-P26 (Taguchi et al, 1998) and SAM-P45 (Suzuki et al, 1997) from Streptomyces albogriseolus have been studied. Pure enzymes (a SAM-P20 homologue isolated from S. coelicolor Müller, SAM-P26 and SAM-P45 from S. albogriseolus), provided by Dr S. Taguchi, were used to study the processing effects on Xys1L in in vitro experiments.…”

A Novel Protein with Alkaline Phosphatase and Protease Inhibitor Activities in Streptomyces hiroshimensis.

“…It appears that S-ALP acts as a multifunctional protein both for dephosphorylation of biologically active intermediates by ALP activity, [1][2][3][4][5] and for the inhibitory regulation of proteases by protease inhibitory activity, similar to the SSI-like proteins. [6][7][8][9][10][11] …”

“…[7][8][9][10] Almost all of these inhibitors exist as dimeric proteins consisting of two identical subunits. 8,10) A novel monomeric subtilisin inhibitor has been isolated from the culture medium of a Streptomyces species 1-72.…”