Moreira Leonilde M, Videira Paula A, Sousa Sílvia A, Leitão Jorge H, Cunha Mónica V, Sá-Correia Isabel
Biological Sciences Research Group, Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
Biochem Biophys Res Commun. 2003 Dec 12;312(2):323-33. doi: 10.1016/j.bbrc.2003.10.118.
Bacteria belonging to the Burkholderia cepacia complex (BCC) are important opportunistic pathogens in patients with cystic fibrosis (CF). Since approximately 80% of the CF isolates examined produce exopolysaccharide (EPS), it was hypothesized that this EPS may play a role in the colonization and persistence of these bacteria in the CF lung. The present study describes the identification and physical organization of the EPS biosynthetic gene cluster. This bce gene cluster was identified following the isolation of three EPS-defective mutants from the highly mucoid CF isolate IST408, belonging to BCC genomovar I, based on random plasposon insertion mutagenesis and comparison of the nucleotide sequence of the interrupted genes with the available genome of Burkholderia cenocepacia J2315. This 16.2 kb cluster includes 12 genes and is located on chromosome 2. Database searches for homologous proteins and secondary structure analysis for the deduced Bce amino acid sequences revealed genes predicted to encode enzymes required for the formation of nucleotide sugar precursors, glycosyltransferases involved in the repeat-unit assembly, and other proteins involved in polymerization and export of bacterial surface polysaccharides.
洋葱伯克霍尔德菌复合体（BCC）中的细菌是囊性纤维化（CF）患者重要的机会致病菌。由于大约80%检测的CF分离株能产生胞外多糖（EPS），因此推测这种EPS可能在这些细菌于CF患者肺部的定植和持续存在中发挥作用。本研究描述了EPS生物合成基因簇的鉴定和物理组织。基于随机转座子插入诱变以及将中断基因的核苷酸序列与洋葱伯克霍尔德菌J2315的可用基因组进行比较，从高度黏液样的CF分离株IST408（属于BCC基因变种I）中分离出三个EPS缺陷型突变体后，鉴定出了这个bce基因簇。这个16.2 kb的基因簇包含12个基因，位于2号染色体上。对同源蛋白的数据库搜索以及对推导的Bce氨基酸序列的二级结构分析揭示了预测编码核苷酸糖前体形成所需酶、参与重复单元组装的糖基转移酶以及参与细菌表面多糖聚合和输出的其他蛋白质的基因。
