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The essentiality and involvement of Streptococcus intermedius histone‐like DNA‐binding protein in bacterial viability and normal growth
Author(s) -
Liu Dali,
Yumoto Hiromichi,
Murakami Keiji,
Hirota Katsuhiko,
Ono Tsuneko,
Nagamune Hideaki,
Kayama Shizuo,
Matsuo Takashi,
Miyake Yoichiro
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06232.x
Subject(s) - biology , nucleoid , streptococcus intermedius , transcription (linguistics) , electrophoretic mobility shift assay , gene , histone , gene expression , transcription factor , microbiology and biotechnology , escherichia coli , rna , genetics , streptococcus , bacteria , linguistics , philosophy
Summary Streptococcus intermedius histone‐like DNA‐binding protein ( Si ‐HLP) is a homodimeric protein and, conserved with Escherichia coli HU, a well‐documented nucleoid‐associated protein (NAP). In E. coli , HU plays important roles as both structural and regulatory factors, but it is not essential for E. coli viability. Streptococcal HLP has been found to bind host cells and induce cytokine production, but its physiological role remains poorly defined. In the present study, using gene insertion knockout and tetracycline‐regulated antisense RNA expression techniques, we determined whether Si ‐HLP is essential for bacterial viability and normal growth in S. intermedius . The Si‐ HLP‐downregulated S. intermedius strain showed alterations in its morphology and surface properties. Downregulation of Si ‐HLP led to an expanded nucleoid to fill the intracellular space. Transcription levels of several genes, including virulence‐associated factors, were found to be activated or repressed in the antisense Si‐hlp RNA‐expressing strain by real‐time PCR and reverse‐transcription PCR. Collectively, these data suggest that Si ‐HLP serves as an essential NAP governing the nucleoid architecture and controlling the gene transcription profile in S. intermedius .