Cloning and sequence of MS fimbrial gene of Serratia marcescens.

根据粘质沙雷氏菌菌毛与抗粘质沙雷氏菌菌毛的血凝或凝集模式的不同，将粘质沙雷氏菌菌毛大致分为三种类型(SMF-1、SMF-2-3)，即甘露糖敏感(MS-)、甘露糖抗性(MR-)和非血凝型。我在粘质链霉菌中发现了两个不同的菌毛(SMF-4、-5)，它们的菌毛亚基的结构或分子大小与SMF-1不同，但它们与SMF-1具有相同的抗原性。将这些菌毛基因分别克隆到大肠杆菌中，分析表明它们的基因组织与大肠杆菌相似，证实SMF-3在亲本菌株US5中没有表达，只有在转移到大肠杆菌中才能表达。SMF-3亚基不含系统，结构独特。虽然未见粘质链霉菌临床分离株与SMF-3抗体发生凝集反应，但约50%的粘质链霉菌与含有SMF-3部分片段的4个Sal I DNA片段探针Southern杂交呈阳性反应。事实上，SMF-3可以从US5以外的一个杂交阳性菌株克隆到大肠杆菌中。我已经测定了主要结构菌毛亚单位基因(SMF-1、-2和-3)的DNA序列。在确定SMF-4和SMF-5的DNA序列后，我将利用它们的DNA序列或氨基酸序列来研究与菌毛的抗原性和形态形成有关的氨基酸序列。

The fimbriae of Serratia marcescens were roughly classified into three types (SMF-1, -2 -3), which were mannose-sensitive- (MS-), mannose-resistant- (MR-) and non-hemagglutinative-fimbriae, according to the difference of their hamagglutination patterns or agglutination patterns with antibodies raised against the fimbriae of S. marcescens. I found two different MS fimbriae (SMF-4, -5) in S. marcescens, whose structure or molecular size of the fimbrial subunits were different from that of SMF-1 though they had the common antigenicity with SMF-1, .Analysis of these fimbrial genes, which were cloned into Escherichia coli respectively, indicated that their gene organization were resemble to that of E. coli.I confirmed that smf-3 was not expressed in the parent strain US5 and was expressed only after it was moved into E. coli. The subunit of SMF-3 seemed to have unique structure because it had contained no system. Though no clinical isolates of S. marcescens were agglutinated with the antibody raised against SMF-3, about 50% strains of them showed positive reaction by Southern hybridization with the four Sal I DNA fragments probes which contained the part of smf-3. Indeed, smf-3 could be cloned into E. coli from one hybridization-positive strain other than US5.I have determined the DNA sequence of the major structural fimbrial subunit genes (smf-1, -2 and -3). After determination of DNA sequence of smf-4 and smf-5 I would investigate the amino acids sequence responsible to antigenicity and morphorogical formation of the fimbriae by using the data of their DNA or amino asids sequence.