Major sperm protein genes from Onchocerca volvulus.

Nematode spermatozoa, unlike their mammalian counterparts, are nonflagellated crawling cells. The pseudopod of these cells contains the major sperm protein (MSP) which comprises more than 15% of the protein in the sperm. MSP is presumed to function as a cytoskeletal element involved in motility. An Ascaris MSP cDNA sequence was used as a probe to identify and isolate Onchocerca volvulus MSP clones from a lambda gt11 genomic library. Two clones, OVGS-1 (765 bp) and OVGS-2 (1765 bp), were characterized by restriction endonuclease mapping and sequence analysis. Both genomic clones contain MSP protein coding regions of 99 and 282 bp separated by an intervening sequence of 153 bp. The genes OVGS-1 and OVGS-2 are 95% similar in nucleotide sequence in the protein coding regions, but only 79% similar in their intron sequences. A number of potential regulatory sequences in the flanking regions and at the exon/intron junctions of the O. volvulus MSP genes are in good agreement with consensus sequences in other eukaryotic cells. The nucleotide sequence of the O. volvulus MSP genes were over 80% similar to the Ascaris MSP cDNA sequence and 79% similar to the Caenorhabditis MSP-3 cDNA. The predicted amino acid sequence of the O. volvulus MSPs were 96% similar to each other, 90-91% similar to Ascaris MSP and 81-82% similar to Caenorhabditis MSP-3. These results offer evidence that the MSP sequences have been highly conserved throughout nematode evolution but are variable in their genomic organization and the presence of introns.