Worm Breeder's Gazette 14(1): 88 (October 1, 1995)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Department of Plant Pathology, University of Georgia Athens, Georgia, 30602-7274
Collagen is the major structural component of nematode cuticles. In Caenorhabditis elegans, the N-terminal regions of cuticle collagen proteins contain the highly conserved motif, R-X-X-R, which has been predicted to contain a potential subtilisin-like proteolytic processing site required for cleavage of the collagen proteins and normal cuticle collagen function (Kramer, 1994, FASEB 8:329-336). Cuticles of adult females of the plant-parasitic nematode Meloidogyne incognita contain a 76 kDa collagen which comprises over 50% of the B- mercaptoethanol-soluble cuticular proteins (Reddigari et al., 1986, J. Nematol. 18:294-302). We determined the N-terminal amino acid sequence of this major collagen and found it to be identical to the predicted amino acid sequence, starting at amino acid number 66, of the M. incognita Lemmi 5 cDNA clone (Van der Eycken et al., 1994, Gene 151:237-242) (Fig.1). A putative subtilisin-like protease recognition site was found immediately upstream of the region of amino acid homology between LEMMI 5 and the N-terminal sequence of the 76 kDa collagen (Fig.1). Our data support previous speculation about the existence of this novel method of collagen maturation and provide further evidence that this mechanism has been conserved during nematode evolution. In addition to protein processing, the expression of the Lemmi 5 gene was transcriptionally regulated: Lemmi 5-specific transcripts were present in adult females but not in eggs or second-stage juveniles. Also, Lemmi 5 analogs were present only in four Meloidogyne species, but not in C. elegans, Heterodera glycines, or tomato. PREDICTED LEMMI5 AMINO ACID SEQUENCE 1M A T L V V M P Q L Y S Q I N D L N L R V R D G V Q A F R V N T D S A W N D L M E L Q V A V T P Q S K P R S * N P F Q S L Y³R Q K R³S L P D Y C I C Q P L E I N79 ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ S L P D Y C I C Q P L E I N CONFIRMED N-TERMINAL AMINO ACID SEQUENCE Figure 1. The partial predicted amino acid sequence (residues 1-79) of the Lemmi 5 collagen gene is shown in roman letters. The putative subtilisin-like protease recognition sequence, R-Q-K-R, is boxed and the first amino acid after the proteolytic cleavage site is indicated by an *. The empirically determined N-terminal sequence of the 76 kDa from adult female M. incognita is italicized.