Tatituri Raju Venkata Veera, Alderwick Luke J, Mishra Arun K, Nigou Jerome, Gilleron Martine, Krumbach Karin, Hitchen Paul, Giordano Assunta, Morris Howard R, Dell Anne, Eggeling Lothar, Besra Gurdyal S
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Institut de Pharmacologie et de Biologie Structurale, UMR CNRS 5089, Toulouse, France.
Microbiology (Reading). 2007 Aug;153(Pt 8):2621-2629. doi: 10.1099/mic.0.2007/008078-0.
Arabinan polysaccharide side-chains are present in both Mycobacterium tuberculosis and Corynebacterium glutamicum in the heteropolysaccharide arabinogalactan (AG), and in M. tuberculosis in the lipoglycan lipoarabinomannan (LAM). This study shows by quantitative sugar and glycosyl linkage analysis that C. glutamicum possesses a much smaller LAM version, Cg-LAM, characterized by single t-Araf residues linked to the alpha(1-->6)-linked mannan backbone. MALDI-TOF MS showed an average molecular mass of 13,800-15 400 Da for Cg-LAM. The biosynthetic origin of Araf residues found in the extracytoplasmic arabinan domain of AG and LAM is well known to be provided by decaprenyl-monophosphoryl-D-arabinose (DPA). However, the characterization of LAM in a C. glutamicum : : ubiA mutant devoid of prenyltransferase activity and devoid of DPA-dependent arabinan deposition into AG revealed partial formation of LAM, albeit with a slightly altered molecular mass. These data suggest that in addition to DPA utilization as an Araf donor, alternative pathways exist in Corynebacterianeae for Araf delivery, possibly via an unknown sugar nucleotide.
阿拉伯聚糖多糖侧链存在于结核分枝杆菌和谷氨酸棒杆菌的杂多糖阿拉伯半乳聚糖（AG）中，以及结核分枝杆菌的脂多糖脂阿拉伯甘露聚糖（LAM）中。本研究通过定量糖和糖基连接分析表明，谷氨酸棒杆菌拥有一个小得多的LAM版本，即Cg-LAM，其特征是单个t-Araf残基与α(1→6)连接的甘露聚糖主链相连。基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）显示Cg-LAM的平均分子量为13,800 - 15,400 Da。众所周知，在AG和LAM的胞外阿拉伯聚糖结构域中发现的Araf残基的生物合成来源由癸异戊烯基单磷酸-D-阿拉伯糖（DPA）提供。然而，在缺乏异戊烯基转移酶活性且缺乏DPA依赖性阿拉伯聚糖沉积到AG中的谷氨酸棒杆菌::ubiA突变体中对LAM的表征显示，LAM部分形成，尽管分子量略有改变。这些数据表明，除了利用DPA作为Araf供体外，棒杆菌科中还存在Araf递送的替代途径，可能是通过一种未知的糖核苷酸。
