Kanbe T, Cutler J E
Laboratory of Medical Mycology, Research Institute for Disease Mechanism and Control, Nagoya University School of Medicine, Showa-ku, Nagoya 466-8550, Japan.
Infect Immun. 1998 Dec;66(12):5812-8. doi: 10.1128/IAI.66.12.5812-5818.1998.
This study was conducted to define adhesive characteristics of the acid-stable moiety of the Candida albicans phosphomannoprotein complex (PMPC) on adherence of this fungus to marginal zone macrophages of the mouse spleen. Complete digestion of the acid-stable moiety (Fr.IIS) of the C. albicans PMPC with an alpha-mannosidase or hydrolysis with 0.6 N sulfuric acid destroyed adhesin activity, as determined by the inability of the soluble digests to inhibit yeast cell adherence to the splenic marginal zone. Fr.IIS adhesin activity was decreased following digestion with an alpha-1,2-specific mannosidase. Oligomannosyls consisting of one to six mannose units, which were isolated from the acid-stable part of the PMPC, did not inhibit yeast cell binding and thus do not function alone as adhesin sites in the PMPC. To gain more insight into the minimum requirements for adhesin activity, PMPCs were isolated from a Saccharomyces cerevisiae wild-type strain and from mutant strains mnn1, mnn2, and mnn4; the PMPCs were designated scwt/Fr.II, scmn1/Fr.II, scmn2/Fr.II, and scmn4/Fr.II, respectively. S. cerevisiae scmn2/Fr.II lacks oligomannosyl side chain branches from the outer core mannan, and scmn2/Fr.II was the only PMPC without adhesin activity. S. cerevisiae scwt/Fr.II, scmn1/Fr.II, and scmn4/Fr.II showed adhesin activities less than that of C. albicans Fr.II. These three S. cerevisiae PMPCs are generally similar to Fr. IIS, except that the S. cerevisiae structure has fewer and shorter side chains. Immunofluorescence microscopy show that the acid-stable part of the PMPC is displayed homogeneously on the C. albicans yeast cell surface, which would be expected for a surface adhesin. Our results indicate that both the mannan core and the oligomannosyl side chains are responsible for the adhesin activity of the acid-stable part of the PMPC.
本研究旨在确定白色念珠菌磷酸甘露糖蛋白复合物（PMPC）的酸稳定部分对该真菌黏附小鼠脾脏边缘区巨噬细胞的黏附特性。用α-甘露糖苷酶完全消化白色念珠菌PMPC的酸稳定部分（Fr.IIS）或用0.6N硫酸水解会破坏黏附素活性，这可通过可溶性消化产物无法抑制酵母细胞黏附到脾脏边缘区来确定。用α-1,2特异性甘露糖苷酶消化后，Fr.IIS黏附素活性降低。从PMPC的酸稳定部分分离出的由一至六个甘露糖单元组成的低聚甘露糖基不抑制酵母细胞结合，因此在PMPC中不能单独作为黏附素位点发挥作用。为了更深入了解黏附素活性的最低要求，从酿酒酵母野生型菌株以及突变菌株mnn1、mnn2和mnn4中分离出PMPC；这些PMPC分别命名为scwt/Fr.II、scmn1/Fr.II、scmn2/Fr.II和scmn4/Fr.II。酿酒酵母scmn2/Fr.II缺乏外核心甘露聚糖的低聚甘露糖基侧链分支，并且scmn2/Fr.II是唯一没有黏附素活性的PMPC。酿酒酵母scwt/Fr.II、scmn1/Fr.II和scmn4/Fr.II的黏附素活性低于白色念珠菌Fr.II。这三种酿酒酵母PMPC与Fr. IIS总体相似，只是酿酒酵母的结构具有更少且更短的侧链。免疫荧光显微镜显示，PMPC的酸稳定部分均匀地展示在白色念珠菌酵母细胞表面，这对于表面黏附素来说是预期的。我们的结果表明，甘露聚糖核心和低聚甘露糖基侧链均对PMPC酸稳定部分的黏附素活性负责。
