Identification of a gene encoding the predicted ribosomal protein L7b divergently transcribed fromPOL1in fission yeastSchizosaccharomyces pombe

Abstract

A 0.85 Kb RNA molecule is transcribed in the region upstream from the 5'-end of the S. pombe POL1 gene encoding the catalytic subunit of DNA polymerase alpha. The nucleotide sequence of the DNA region hybridizing with the 0.85 Kb transcript allowed us to identify an open reading frame coding for a predicted peptide which shows 50% identity with the rat ribosomal protein L7 and which is transcribed divergently from POL1. We have named this gene RPL7b because of the existence in S. pombe of a different sequence, named RPL7, which also codes for a putative protein showing homology with the rat ribosomal protein L7. The RPL7b gene includes a 291 bp-long intron containing the sequences necessary for intron excision and RNA splicing in S. pombe. The precise location of the intron was established by amplification and sequencing of a partial cDNA copy of the mRNA, whereas the initiation site of transcription was determined by reverse transcription of the 5' region of the mRNA. The 320 bp separating the starting methionine codons of RPL7b and POL1 genes should contain the signals necessary for their divergent transcription and regulation. The sequence 5'-AAGACAGTCACA-3', whose primary structure is homologous to a conserved block present in the 5'-untranscribed regions of other S. pombe genes of ribosomal proteins, is located about 50 bp upstream the transcription initiation site of RPL7b.

The CAGTCACA box in the fission yeast Schizosaccharomyces pombe functions like a TATA element and binds a novel factor.

“…Fourteen known rp gene promoters from the fission yeast Schizosaccharomyces pombe share common sequences in the promoter region. We have named these common elements homol A, B, C and D (Nischt et al, 1987;Gross et al, 1988;Gatermann et al, 1989a;Teletski and Kaufer, 1989;Murray and Watts, 1990;Beltrame and Bianchi, 1990;Damagnez et al, 1991;Kwart et al, 1991). The position and degeneracy of the homol A, B and C elements in these promoters make them good candidates for upstream activating sequences (UAS) as found for rp genes in the budding yeast S.cerevisiae (Mager, 1988).…”

Two distinct yeast proteins are related to the mammalian ribosomal polypeptide L7

“…The coding sequence of YL8, in contrast, has a high codon adaptative index (0-78), as do all ribosomal protein genes analysed so far in S. cerevisiae (Sharp and Cowe, 1991). Remarkably, the RL7a and RL7b gene products of S. pombe also differ substantially in their sequence (Murray and Watts, 1990;Damagnez et al, 1991) and their codon usage (see Sharp et al, 1988). The RL7b sequence, which is more closely related to YL8 than RL7a is, has a codon usage that is typical of highly expressed proteins in S. pombe, whereas RL7a has a lower codon bias (Sharp et al, 1988).…”

“…A survey of current protein databanks showed a strong sequence homology between RLP7p and the evolutionary conserved ribosomal polypeptide L7 (Lin et al, 1987;Meyhuas and Klein, 1990) of mammals (see Figure 3A). In addition to the mammalian polypeptides, the L7 family includes a hypothetical Dictyostelium discoideum gene product (Szymkowski et al, 1989), the related but distinct gene products RL7a and RL7b of Schizosaccharomyces pombe (Murray and Watts, 1990;Damagnez et al, 1991), and the YL8 ribosomal polypeptide of S. cerevisiae (Otaka et al, 1984;Mizuta et al, 1992). The L7-like proteins are about 250 amino acids long and are 50-60% identical (Mizuta et al, 1992), but differ by a variable amino-terminal hydrophilic domain.…”

Comparative Analysis of mRNA and lncRNA Expression Profiles in Testicular Tissue of Sexually Immature and Sexually Mature Mongolian Horses

“…During this stage, male individuals undergo rapid physical growth and organ development, and their demand for protein is particularly high [ 97 ]. The RPL7 gene, through its encoded ribosomal protein, actively participates in the biosynthetic process of proteins, ensuring that all parts of the body receive an adequate and high-quality supply of proteins to support the healthy growth of male animals [ 98 ]. In addition, the RPL7 protein exhibits RNA binding activity and transcriptional regulatory ability, both of which play a pivotal role in the regulation of gene expression within cells [ 99 , 100 ].…”