The rIIA gene of bacteriophage T4. I. Its DNA sequence and discovery of a new open reading frame between genes 60 and rIIA.

Abstract

We have determined the DNA sequence of the rIIA gene and have discovered a small open reading frame, rIIA.1, between genes 60 and rIIA. The predicted molecular weights of these proteins are 82,840 for rIIA and 8,124 for rIIA.1. The rIIA protein has a repeated motif which suggests that the gene has evolved by duplication. It also has a motif which suggests that it belongs to a group of ompR-like proteins that control regulation of gene expression in response to changes in the external environment. We have sequenced three different missense mutants whose mutations lie in the Ala segment of the rIIA genetic map. All three changes are found within the first 35 bp of the rIIA coding sequence. The region of control of protein synthesis is identical in the rIIA gene and in gene 44 of T4. We relate this finding to the high sensitivity of both RNAs to translational repression by the T4 regA gene product.

The rIIA gene of bacteriophage T4. II. Regulation of its messenger RNA synthesis.

“…There is a third 5' end which maps between the two described above, also in the coding region of ORF rZZA.1. This 5' end maps to the T, at 405 in the sequence given in Figure 2 of DAEGELEN and BRODY (1990). Examining the DNA sequence upstream of this 5' end, we find a -10 TAGAAT sequence 1 bp different from the E. coli -10 consensus sequence, and a -35 TTGATA box again 1 bp different from the E. coli consensus sequence.…”

“…It maps to the G at position 313 of our sequence, just before the ORF rZZA. 1 (see Figure 2 of DAEGELEN and BRODY 1990). This 5' end implies a -10 sequence of TATAAT, and a -35 sequence of TTTACT, with a 17-bp spacer; these three elements are frequently found in the T4 genome as early promoters.…”

“…It is also clear from Figure 3 that some rZlA RNA is synthesized starting at promoters upstream of P1. We have not DAEGELEN and BRODY 1990) was sequenced by the SANGERdideoxynucleotide chain-termination method using the Klenow DNA polymerase (SANGER, NICKLEN and COULSON 1977). The products of the reaction were analyzed on a denaturing 6% polyacrylamide gel (lanes a, b, c and d).…”

“…A LTHOUGH the rZZA gene of bacteriophage T 4 has played an important role in the history of genetics, its role in the T 4 life cycle is still obscure [see the companion study (DAEGELEN and BRODY 1990); and SINGER, SHINEDLING and GOLD 1983)l. T h e control of biosynthesis of the rZZA gene product is also not fully understood. The rZZA gene is part of an early transcription unit (a transcription unit for which initiation of RNA synthesis requires n o T 4 proteins).…”

“…From left to right: (A) Nucleotide sequence of gene rIIA. Single-stranded DNA purified from the 437-bp Alul-AccI T 4 DNA fragment cloned into M 1 Smpl8 (seeDAEGELEN and BRODY 1990) was sequenced by the SANGERdideoxynucleotide chain-termination method using the Klenow DNA polymerase(SANGER, NICKLEN and COULSON 1977). The products of the reaction were analyzed on a denaturing 6% polyacrylamide gel (lanes a, b, c and d).…”