Modeling the structure of the type I peritrophic matrix: characterization of a Mamestra configurata intestinal mucin and a novel peritrophin containing 19 chitin binding domains.
Twelve to fourteen integral proteins were found to reside in the Type I peritrophic matrix (PM) of Mamestra configurata (bertha armyworm) larvae. Several methods were employed, including de novo peptide sequencing, the generation of a midgut-specific EST database and immunological screening, which led to the isolation of cDNAs encoding two integral PM proteins. McPM1, the largest PM protein described to date at 202 kDa, was comprised of a concatamer of 19 chitin binding domains (CBD), 12 of which resided within a central repetitive region consisting of six iterations of a two CBD module. The protein was found to reside within the PM primarily as several lower molecular weight, presumably proteolytically processed, forms. McMUC1 was similar in structure to other insect intestinal mucins (IIM) and was highly glycosylated. The expression of both proteins was restricted to the larval midgut. Lower molecular weight proteins that may represent non- and partially glycosylated forms of McMUC1 were also recognized by an anti-McMUC1 antiserum. These were preferentially degraded upon ingestion of M. configurata multi-capsid nucleopolyhedrovirus by larvae, possibly by a viral-encoded metalloprotease. A molecular model of PM structure is presented featuring the interaction of McPM1 with chitin inter-fibril junctions and McMUC1 with the extended chains in the internodal regions. The potential for interaction between PM proteins via intermolecular disulfide bond formation and through association of CBD with N-linked glycans is discussed.
Molecular Genetics Department, Agriculture and Agri-Food Canada, University of Saskatchewan, 107 Science Place, Saskatoon, SK, S7N OX2, Canada.
Xianzong
X
Shi
Mahmood
M
Chamankhah
Savita
S
Visal-Shah
Sean M
SM
Hemmingsen
Martin
M
Erlandson
Lorraine
L
Braun
Michelle
M
Alting-Mees
George G
GG
Khachatourians
Michael
M
O'grady
Dwayne D
DD
Hegedus
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002686:Chitin / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007422:Intestines / Q000737:chemistry; D007814:Larva / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009036:Moths / Q000737:chemistry* / Q000235:genetics; D009077:Mucins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D018076:DNA, Complementary; D019476:Insect Proteins; D009077:Mucins; D002686:Chitin