A 38 nt region and its flanking sequences within gag of Friend murine leukemia virus are crucial for splicing at the correct 5 ' and 3 ' splice sites

作者：Machinaga Akihito; Takase Yoden Sayaka^*

来源：Microbiology and Immunology, 2014, 58(1): 38-50.

DOI：10.1111/1348-0421.12114

• murine leukemia virus
• gag gene
• splicing
• env-mRNA

The genome of the Friend murine leukemia virus (Fr-MLV) contains a 5 ' splice site (5 ' ss) located at 205 nt and a 3 ' ss located at 5489 nt. In our previous studies, it was shown that if the HindIII-BglII (879-1904 bp) fragment within gag is deleted from the proA8m1 vector, which carries the entire Fr-MLV sequence, then cryptic splicing of env-mRNA occurs. Here, attempts were made to identify the genomic segment(s) in this region that is/are essential to correct splicing. First, vectors with a serially truncated HindIII-BglII fragment were constructed. The vector, in which a 38 bp fragment (1612-1649 bp) is deleted or reversed in proA8m1, only produced splice variants. It was found that a 38 nt region within gag contains important elements that positively regulate splicing at the correct splice sites. Further analyses of a series of vectors carrying the 38 bp fragment and its flanking sequences showed that a region (1183-1611 nt) upstream of the 38 nt fragment also contains sequences that positively or negatively influence splicing at the correct splice sites. The SphI-NdeI (5140-5400 bp) fragment just upstream of the 3 ' ss was deleted from vectors that carried the 38 bp fragment and its flanking sequences, which yielded correctly spliced mRNA; interestingly, these deleted vectors showed cryptic splicing. These findings suggest that the 5140-5400 nt region located just upstream of the 3 ' ss is required for the splicing function of the 38 nt fragment and its flanking sequences.

• 出版日期2014-1