Bertram Ralph, Schlicht Maximilian, Mahr Kerstin, Nothaft Harald, Saier Milton H, Titgemeyer Fritz
Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
J Bacteriol. 2004 Mar;186(5):1362-73. doi: 10.1128/JB.186.5.1362-1373.2004.
Streptomyces coelicolor is the prototype for the investigation of antibiotic-producing and differentiating actinomycetes. As soil bacteria, streptomycetes can metabolize a wide variety of carbon sources and are hence vested with various specific permeases. Their activity and regulation substantially determine the nutritional state of the cell and, therefore, influence morphogenesis and antibiotic production. We have surveyed the genome of S. coelicolor A3(2) to provide a thorough description of the carbohydrate uptake systems. Among 81 ATP-binding cassette (ABC) permeases that are present in the genome, we found 45 to encode a putative solute binding protein, an essential feature for carbohydrate permease function. Similarity analysis allowed the prediction of putative ABC systems for transport of cellobiose and cellotriose, alpha-glucosides, lactose, maltose, maltodextrins, ribose, sugar alcohols, xylose, and beta-xylosides. A novel putative bifunctional protein composed of a substrate binding and a membrane-spanning moiety is likely to account for ribose or ribonucleoside uptake. Glucose may be incorporated by a proton-driven symporter of the major facilitator superfamily while a putative sodium-dependent permease of the solute-sodium symporter family may mediate uptake of galactose and a facilitator protein of the major intrinsic protein family may internalize glycerol. Of the predicted gene clusters, reverse transcriptase PCRs showed active gene expression in 8 of 11 systems. Together with the previously surveyed permeases of the phosphotransferase system that accounts for the uptake of fructose and N-acetylglucosamine, the genome of S. coelicolor encodes at least 53 potential carbohydrate uptake systems.
天蓝色链霉菌是用于研究抗生素产生和分化的放线菌的原型。作为土壤细菌,链霉菌能够代谢多种碳源,因此具有各种特定的通透酶。它们的活性和调控在很大程度上决定了细胞的营养状态,进而影响形态发生和抗生素生产。我们对天蓝色链霉菌A3(2)的基因组进行了调查,以全面描述碳水化合物摄取系统。在基因组中存在的81个ATP结合盒(ABC)通透酶中,我们发现45个编码假定的溶质结合蛋白,这是碳水化合物通透酶功能的一个基本特征。相似性分析使得能够预测用于转运纤维二糖和纤维三糖、α-葡萄糖苷、乳糖、麦芽糖、麦芽糊精、核糖、糖醇、木糖和β-木糖苷的假定ABC系统。一种由底物结合部分和跨膜部分组成的新型假定双功能蛋白可能负责核糖或核糖核苷的摄取。葡萄糖可能通过主要促进剂超家族的质子驱动同向转运体进入细胞,而溶质-钠同向转运体家族的一种假定的钠依赖性通透酶可能介导半乳糖的摄取,主要内在蛋白家族的一种促进剂蛋白可能使甘油内化。在预测的基因簇中,逆转录酶PCR显示11个系统中有8个系统的基因表达活跃。连同先前调查的负责果糖和N-乙酰葡糖胺摄取的磷酸转移酶系统的通透酶一起,天蓝色链霉菌的基因组编码至少53个潜在的碳水化合物摄取系统。