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.