Conservation in the 5' flanking sequences of transcribed members of the Caenorhabditis elegans major sperm protein gene family

Abstract

The major sperm proteins (MSPs) are encoded in the Caenorhabditis genome by a multigene family with more than 50 genes dispersed in small clusters at three chromosomal loci. In spite of their dispersed locations, all of the MSP genes appear to be expressed at the same time exclusively in the testis, indicating co-ordinate temporal and spatial regulation of these dispersed genes. Many of the MSP genes must be transcribed, because RNA hybridization with gene-specific probes showed that individual genes each contribute less than 3% to the total poly(A)+ RNA, and 13 out of 14 sequenced cDNAs came from different genes. Primer extension assays from MSP mRNA showed that most of the MSP mRNAs must be initiated at position -35 from the translation start codon. Extensive similarity was found in the first 100 nucleotides of genomic sequence flanking the start codons of ten MSP genes from different chromosomal locations. All MSP genes contained a consensus ribosome binding site, a consensus TATA homology 27 nucleotides distal to the site of mRNA initiation, and ten highly conserved nucleotides adjacent to the site of initiation. All the MSP genes contained the sequence AGATCT located approximately 65 nucleotides upstream from the transcriptional start, but little or no similarity was found more distal to this. Some of these conserved sequences may be cis-acting control elements that ensure the cell and temporal specificity of transcription of these co-ordinately regulated genes.