Barrangou Rodolphe, Azcarate-Peril M Andrea, Duong Tri, Conners Shannon B, Kelly Robert M, Klaenhammer Todd R
Genomic Sciences Graduate Program, North Carolina State University, Raleigh, NC 27695, USA.
Proc Natl Acad Sci U S A. 2006 Mar 7;103(10):3816-21. doi: 10.1073/pnas.0511287103. Epub 2006 Feb 27.
The transport and catabolic machinery involved in carbohydrate utilization by Lactobacillus acidophilus was characterized genetically by using whole-genome cDNA microarrays. Global transcriptional profiles were determined for growth on glucose, fructose, sucrose, lactose, galactose, trehalose, raffinose, and fructooligosaccharides. Hybridizations were carried out by using a round-robin design, and microarray data were analyzed with a two-stage mixed model ANOVA. Differentially expressed genes were visualized by hierarchical clustering, volcano plots, and contour plots. Overall, only 63 genes (3% of the genome) showed a >4-fold induction. Specifically, transporters of the phosphoenolpyruvate:sugar transferase system were identified for uptake of glucose, fructose, sucrose, and trehalose, whereas ATP-binding cassette transporters were identified for uptake of raffinose and fructooligosaccharides. A member of the LacS subfamily of galactoside-pentose hexuronide translocators was identified for uptake of galactose and lactose. Saccharolytic enzymes likely involved in the metabolism of monosaccharides, disaccharides, and polysaccharides into substrates of glycolysis were also found, including enzymatic machinery of the Leloir pathway. The transcriptome appeared to be regulated by carbon catabolite repression. Although substrate-specific carbohydrate transporters and hydrolases were regulated at the transcriptional level, genes encoding regulatory proteins CcpA, Hpr, HprK/P, and EI were consistently highly expressed. Genes central to glycolysis were among the most highly expressed in the genome. Collectively, microarray data revealed that coordinated and regulated transcription of genes involved in sugar uptake and metabolism is based on the specific carbohydrate provided. L. acidophilus's adaptability to environmental conditions likely contributes to its competitive ability for limited carbohydrate sources available in the human gastrointestinal tract.
利用全基因组cDNA微阵列从基因层面表征了嗜酸乳杆菌参与碳水化合物利用的转运和分解代谢机制。测定了嗜酸乳杆菌在葡萄糖、果糖、蔗糖、乳糖、半乳糖、海藻糖、棉子糖和低聚果糖上生长时的全局转录谱。杂交采用循环设计进行，微阵列数据用两阶段混合模型方差分析进行分析。通过层次聚类、火山图和等高线图对差异表达基因进行可视化。总体而言，只有63个基因（占基因组的3%）显示出>4倍的诱导。具体来说，磷酸烯醇丙酮酸：糖转运酶系统的转运蛋白被鉴定为负责葡萄糖、果糖、蔗糖和海藻糖的摄取，而ATP结合盒转运蛋白被鉴定为负责棉子糖和低聚果糖的摄取。半乳糖苷-戊糖己糖醛酸转运体LacS亚家族的一个成员被鉴定为负责半乳糖和乳糖的摄取。还发现了可能参与单糖、二糖和多糖代谢为糖酵解底物的糖分解酶，包括Leloir途径的酶机制。转录组似乎受碳分解代谢物阻遏调控。尽管底物特异性碳水化合物转运蛋白和水解酶在转录水平受到调控，但编码调控蛋白CcpA、Hpr、HprK/P和EI的基因始终高度表达。糖酵解核心基因是基因组中表达最高的基因之一。总体而言，微阵列数据显示，参与糖摄取和代谢的基因的协调和调控转录是基于所提供的特定碳水化合物。嗜酸乳杆菌对环境条件的适应性可能有助于其在人类胃肠道中有限碳水化合物来源的竞争能力。
