Capozzi Vittorio, Arena Mattia Pia, Crisetti Elisabetta, Spano Giuseppe, Fiocco Daniela
Department of Food Science, University of Foggia, via Napoli 25, 71122 Foggia, Italy; E-Mails:
Int J Mol Sci. 2011;12(8):5390-405. doi: 10.3390/ijms12085390. Epub 2011 Aug 22.
Small heat shock proteins (sHsps) are ubiquitous conserved chaperone-like proteins involved in cellular proteins protection under stressful conditions. In this study, a reverse transcription quantitative PCR (RT-qPCR) procedure was developed and used to quantify the transcript level of a small heat shock gene (shs) in the probiotic bacterium Lactobacillus acidophilus NCFM, under stress conditions such as heat (45 °C and 53 °C), bile (0.3% w/v), hyperosmosis (1 M and 2.5 M NaCl), and low pH value (pH 4). The shs gene of L. acidophilus NCFM was induced by salt, high temperature and acidic stress, while repression was observed upon bile stress. Analysis of the 5' noncoding region of the hsp16 gene reveals the presence of an inverted repeat (IR) sequence (TTAGCACTC-N9-GAGTGCTAA) homologue to the controlling IR of chaperone expression (CIRCE) elements found in the upstream regulatory region of Gram-positive heat shock operons, suggesting that the hsp16 gene of L. acidophilus might be transcriptionally controlled by HrcA. In addition, the alignment of several small heat shock proteins identified so far in lactic acid bacteria, reveals that the Hsp16 of L. acidophilus exhibits a strong evolutionary relationship with members of the Lactobacillus acidophilus group.
小分子热休克蛋白（sHsps）是普遍存在的保守的伴侣样蛋白，在应激条件下参与细胞蛋白质保护。在本研究中，开发了一种逆转录定量PCR（RT-qPCR）方法，并用于定量益生菌嗜酸乳杆菌NCFM中一个小分子热休克基因（shs）在热（45℃和53℃）、胆汁（0.3% w/v）、高渗（1 M和2.5 M NaCl）和低pH值（pH 4）等应激条件下的转录水平。嗜酸乳杆菌NCFM的shs基因在盐、高温和酸性应激下被诱导，而在胆汁应激下则受到抑制。对hsp16基因5'非编码区的分析揭示了存在一个反向重复（IR）序列（TTAGCACTC-N9-GAGTGCTAA），与革兰氏阳性热休克操纵子上游调控区中发现的伴侣蛋白表达控制IR（CIRCE）元件同源，这表明嗜酸乳杆菌的hsp16基因可能受HrcA转录调控。此外，对目前在乳酸菌中鉴定出的几种小分子热休克蛋白的比对显示，嗜酸乳杆菌的Hsp16与嗜酸乳杆菌组的成员具有很强的进化关系。
