The characterization of DNA-binding protein from Streptococcus intermediusand elucidate its virulence mechanism

点击翻译按钮获取中文摘要

The histone-like proteins (HLPs) play a role in DNA replication, recombination, repair, Mutransposition, and regulation of gene transcription. In addition to their roles in cellular processes, HLPs are considered as an adhesin of some bacteria such as Streptococcus pyogenes. In the present study we cloned a gene encoding a histone-l ike protein (HLPSi) from Streptococcus intermediusUNS46. The deduced amino acid sequence of HLPSi showed 90.1%, 71.6%, 62.5%, 60.7%, and 36.4% identity with a histone-like protein of S. pyogenes A374, Bacillus subtilis, Escherichis coli HU-1, E.coli HU-2, and Mycobacterium leprae TN, respectively. HLPSi was rich in alanine (20.9%), lysine (13.2%), and arginine (4.4%) and devoid of tryptophan, tyrosine, histidine, and cysteine. The recombinant protein was expressed in E.coli JM109 by use of the pGEX expression system. Comparison of the deduced amino acid sequence of HLPSi with known protein sequences deposited in databases revealed that this protein had 90.1%, 71.6%, 62.5%, 60.7% and 36.4% identity over 91 aa residues with histone-like DNA-binding proteins of S.pyogenes A374, Bacillus subtilis, E.coli HU-1 and HU-2, and M. leprae TN, respectively. Anti HLPSi antibody reacted the whole cells of S. intermedius NCDO2227, S.pyogenesA374, S anginosus TW1751. S.constellatus NCD02226, S.inutans lngbritt, S.sobrinus 0MZ65, S.sanguinis ATCC10556, S. sanguinis ST6, S.gordonii Challis, S.salivarius HT9R, S. salivarius NCTC8168, S.mitis ATCC15913, S. aureus Smith, S. aureus SMF-4. Although the export mechanism of HLPSI is still unknown, this is perhaps due to the release of the protein during induced alterations in membrane permeability, leading to the release of this protein along with other cytoplasmic proteins. Further experiments are necessary to define the various aspects of the binding function of HLPSi to host cells.