Molecular characterization of a c-type lysozyme from the desert locust, Schistocerca gregaria (Orthoptera: Acrididae).
Amr A Mohamed, Long Zhang, Moataza A Dorrah, Mohamed Elmogy, Hesham A Yousef, Taha T M Bassal, Bernard Duvic
Author Information
Amr A Mohamed: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt. Electronic address: mamr@sci.cu.edu.eg.
Long Zhang: Key Lab for Biological Control of the Ministry of Agriculture, Department of Entomology, China Agricultural University, Beijing, 100193, PR China.
Moataza A Dorrah: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt.
Mohamed Elmogy: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt.
Hesham A Yousef: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt.
Taha T M Bassal: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt.
Bernard Duvic: Unité DGIMI UMR INRA-UM 1333, Université Montpellier, Place Eugène Bataillon, Montpellier, France.
Lysozymes are bacteriolytic peptides that are implicated in the insect nonspecific innate immune responses. In this study, a full-length cDNA encoding a c-type lysozyme from Schistocerca gregaria (SgLys) has been cloned and characterized from the fat body of immune-challenged 5(th) instar. The deduced mature lysozyme is 119 amino acid residues in length, has a calculated molecular mass of 13.4 kDa and an isoelectric point (Ip) of 9.2. SgLys showed high identities with other insect lysozymes, ranging from 41.5% to 93.3% by BLASTp search in NCBI. Eukaryotic in vitro expression of the SgLys ORF (rSgLys) with an apparent molecular mass of ∼16 kDa under SDS-PAGE is close to the calculated molecular weight of the full-length protein. rSgLys displayed growth inhibitory activity against Gram-negative and Gram-positive bacteria. 3D structure modeling of SgLys, based on comparison with that of silkworm lysozyme, and sequence comparison with the helix-loop-helix (α-hairpin) structure of hen egg white lysozyme (HEWL) were employed to interpret the antibacterial potencies. Phylogenetic alignments indicate that SgLys aligns well with insect c-type lysozymes that expressed principally in fat body and hemocytes and whose role has been defined as immune-related. Western blot analysis showed that SgLys expression was highest at 6-12 h post-bacterial challenge and subsequently decreased with time. Transcriptional profiles of SgLys were determined by semi-quantitative RT-PCR analysis. SgLys transcript was upregulated at the highest level in fat body, hemocytes, salivary gland, thoracic muscles, and epidermal tissue. It was expressed in all developmental stages from egg to adult. These data indicate that SgLys is a predominant acute-phase protein that is expressed and upregulated upon immune challenge.
