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Insect Biochem Mol Biol. 2015 Jul;62:75-85. doi: 10.1016/j.ibmb.2014.12.006. Epub 2014 Dec 29.

Structural features, evolutionary relationships, and transcriptional regulation of C-type lectin-domain proteins in Manduca sexta.

Author information

1
School of Plant Protection, Anhui Agricultural University, Hefei, Anhui 230036, PR China.
2
Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
3
Boyce Thompson Institute, Cornell University, Ithaca, NY 14853, USA.
4
Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA.
5
Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA.
6
Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA. Electronic address: haobo.jiang@okstate.edu.

Abstract

C-type lectins (CTLs) are a large family of Ca(2+)-dependent carbohydrate-binding proteins recognizing various glycoconjugates and functioning primarily in immunity and cell adhesion. We have identified 34 CTLDP (for CTL-domain protein) genes in the Manduca sexta genome, which encode proteins with one to three CTL domains. CTL-S1 through S9 (S for simple) have one or three CTL domains; immulectin-1 through 19 have two CTL domains; CTL-X1 through X6 (X for complex) have one or two CTL domains along with other structural modules. Nine simple CTLs and seventeen immulectins have a signal peptide and are likely extracellular. Five complex CTLs have both an N-terminal signal peptide and a C-terminal transmembrane region, indicating that they are membrane anchored. Immulectins exist broadly in Lepidoptera and lineage-specific gene duplications have generated three clusters of fourteen genes in the M. sexta genome, thirteen of which have similar expression patterns. In contrast to the family expansion, CTL-S1∼S6, S8, and X1∼X6 have 1:1 orthologs in at least four lepidopteran/dipteran/coleopteran species, suggestive of conserved functions in a wide range of holometabolous insects. Structural modeling suggests the key residues for Ca(2+)-dependent or independent binding of certain carbohydrates by CTL domains. Promoter analysis identified putative κB motifs in eighteen of the CTL genes, which did not have a strong correlation with immune inducibility in the mRNA or protein levels. Together, the gene identification, sequence comparisons, structure modeling, phylogenetic analysis, and expression profiling establish a solid foundation for future studies of M. sexta CTL-domain proteins.

KEYWORDS:

Carbohydrate recognition domain; Comparative genomics; Expression profiling; Insect immunity; Pattern recognition

PMID:
25554596
PMCID:
PMC4476918
DOI:
10.1016/j.ibmb.2014.12.006
[Indexed for MEDLINE]
Free PMC Article

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