Saarimaa C, Peltola M, Raulio M, Neu T R, Salkinoja-Salonen M S, Neubauer P
Bioprocess Engineering Laboratory, Department of Process and Environmental Engineering, University of Oulu, P.O. Box 4300, FI-90014 Oulun Yliopisto, Finland.
J Bacteriol. 2006 Oct;188(19):7016-21. doi: 10.1128/JB.00608-06.
Deinococcus geothermalis E50051 forms tenuous biofilms on paper machine surfaces. Field emission electron microscopy analysis revealed peritrichous appendages which mediated cell-to-surface and cell-to-cell interactions but were absent in planktonically grown cells. The major protein component of the extracellular extract of D. geothermalis had an N-terminal sequence similar to the fimbrial protein pilin annotated in the D. geothermalis DSM 11300 draft sequence. It also showed similarity to the type IV pilin sequence of D. radiodurans and several gram-negative pathogenic bacteria. Other proteins in the extract had N-terminal sequences identical to D. geothermalis proteins with conservative motifs for serine proteases, metallophosphoesterases, and proteins whose function is unknown. Periodic acid-Schiff staining for carbohydrates indicated that these extracellular proteins may be glycosylated. A further confirmation for the presence of glycoconjugates on the cell surface was obtained by confocal laser scanning imaging of living D. geothermalis cells stained with Amaranthus caudatus lectin, which specifically binds to galactose residues. The results indicate that the thread-like appendages of D. geothermalis E50051 are glycosylated type IV pili, bacterial attachment organelles which have thus far not been described for the genus Deinococcus.
嗜热栖热放线菌E50051在造纸机表面形成脆弱的生物膜。场发射电子显微镜分析显示，该菌有周毛附属物，介导细胞与表面以及细胞与细胞之间的相互作用，但在浮游生长的细胞中不存在。嗜热栖热放线菌细胞外提取物的主要蛋白质成分的N端序列与嗜热栖热放线菌DSM 11300草图序列中注释的菌毛蛋白菌毛素相似。它还与耐辐射栖热放线菌的IV型菌毛序列以及几种革兰氏阴性病原菌的序列相似。提取物中的其他蛋白质的N端序列与嗜热栖热放线菌的蛋白质相同，具有丝氨酸蛋白酶、金属磷酸酯酶以及功能未知的蛋白质的保守基序。碳水化合物的过碘酸希夫染色表明这些细胞外蛋白质可能被糖基化。通过用尾穗苋凝集素对活的嗜热栖热放线菌细胞进行共聚焦激光扫描成像，进一步证实了细胞表面存在糖缀合物，尾穗苋凝集素能特异性结合半乳糖残基。结果表明，嗜热栖热放线菌E50051的丝状附属物是糖基化的IV型菌毛，这是迄今为止在栖热放线菌属中尚未描述过的细菌附着细胞器。
