Båga M, Göransson M, Normark S, Uhlin B E
Department of Microbiology, University of Umeå, Sweden.
Cell. 1988 Jan 29;52(2):197-206. doi: 10.1016/0092-8674(88)90508-9.
E. coli expressing the papA-I genes produce pili that mediate specific adhesion to mammalian cells. We show that the major pilus subunit gene, papA, is part of a polycistronic transcriptional unit subject to specific posttranscriptional processing. A primary transcript also encoding the papB regulatory gene product is endonucleolytically cleaved, resulting in the rapid decay of the papB-encoding 5' half of the mRNA, whereas the papA-encoding 3' half remains as a quite stable transcript. Processing and differential mRNA stability thereby result in accumulation of mRNAs encoding only the major pilus subunit. A sequence immediately downstream of the papA coding region may serve as a stability determinant for the papA transcript and concomitantly attenuate read-through transcription into the minor pilus subunit gene papH. This suggests that differential expression of genes within an operon may include endo- and exonucleolytic processing of the mRNA.
表达papA - I基因的大肠杆菌产生的菌毛介导与哺乳动物细胞的特异性黏附。我们发现，主要菌毛亚基基因papA是一个多顺反子转录单元的一部分，该转录单元经历特定的转录后加工。一个也编码papB调控基因产物的初级转录本被内切核酸酶切割，导致编码papB的mRNA的5' 端一半快速降解，而编码papA的3' 端一半则作为相当稳定的转录本保留下来。加工过程和不同的mRNA稳定性从而导致仅编码主要菌毛亚基的mRNA积累。papA编码区下游紧邻的一个序列可能作为papA转录本的稳定性决定因素，并同时减弱向次要菌毛亚基基因papH的通读转录。这表明操纵子内基因的差异表达可能包括mRNA的内切和外切核酸酶加工。
