| Summary: | 碩士 === 國立清華大學 === 生物資訊與結構生物研究所 === 94 === Abstract
The flagellar system of Helicobacter pylori, which comprises more than 40 genes, is essential for colonization of the bacterium on human stomach mucosa. A flagellum consists of several major elements. These structural elements are (i) the basal body, (ii) the hook, (iii) the filament and its distal cap. The flaG operon of H. pylori consists of flaG (flagullin protein), fliD (Cap protein HAP2), and fliS (flagullin chaperon) genes under the control of a σ28-dependent promoter. The locus hp0751 of H. pylori strain 26695 is a putative flaG gene, which encodes one of polar flagellin. In other bacterial species report, the mutation in the flaG gene caused an elongated flagellar filament. Also, the mutation flaG gene would affect motility properties of bacteria. However, the real biological function of FlaG protein is not clear. NT-HpFlaG is the N-terminal truncate protein of FlaG of H. pylori 26695. Through NCBI sequence BLAST analysis, we found that N-term of HpFlaG sequence homology with other species was very low. So we focused on NT-HpFlaG and solved the crystal structure of NT-HpFlaG at 2.8 resolution by MAD method. The crystal structure of NT-HpFlaG monomer included two helices and three strands. A structure-based homology analysis with the DALI algorithm indicates that HpFlaG has a novel fold. Two monomers interacted each other by hydrophobic force of coil-coil. We suggested that dimmer might represent the functional state of HpFlaG.
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