[A new early gene in front of the middle gene 31 of bacteriophage T4: cloning and expression].

We have identified a new gene, which we designated gene 31.1, as the nearest upstream neighbour of gene 31. We cloned the 1.03 k.b. EcoRI/BglII fragment of T4 DNA, and expressed both genes using the T7 RNA polymerase/promoter two plasmid system. Gene 31.1 encodes a protein with molecular weight of about 10 kDa, and the C-terminal portion of this gene is the incomplete open reading frame ORF 31.1 determined earlier. Using primer extension sequencing on RNA templates isolated from T4 mot A+ and mot A- infected cells, we have shown that gene 31 has a middle mode mot A-dependent transcript starting at two points and which is initiated from gene's 31 own promoter. Gene 31 is also transcribed from an early upstream promoter into a polycistronic mRNA which covers an early gene 31.1 as well.