Crystal structure of Bombyx mori lipoprotein 6: comparative structural analysis of the 30-kDa lipoprotein family.
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ABSTRACT:
SUBMITTER: Pietrzyk AJ
PROVIDER: S-EPMC4224370 | biostudies-literature | 2014
REPOSITORIES: biostudies-literature
Publications
Crystal structure of Bombyx mori lipoprotein 6: comparative structural analysis of the 30-kDa lipoprotein family.
Pietrzyk Agnieszka J AJ Bujacz Anna A Łochynska Malgorzata M Jaskolski Mariusz M Bujacz Grzegorz G
PloS one 20141107 11
The 30-kDa lipoprotein (LP) family of mulberry silkworm comprises major hemolymph proteins specific to the fifth instar larvae. The family consists of 46 members, 24 of which are referred to as typical 30-kDa LPs. To date, two crystal structures of 30-kDa LPs from Bombyx mori have been described (Bmlp3 and Bmlp7). Here, we present the crystal structure of Bmlp6, another 30-kDa LP member. Bmlp6 is comprised of two domains characteristic of this family, the VHS-type N-terminal domain and β-trefoil ...[more]
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Project description:BACKGROUND: Glucosidation plays a major role in the inactivation and excretion of a great variety of both endogenous and exogenous compounds. A class of UDP-glycosyltransferases (UGTs) is involved in this process. Insect UGTs play important roles in several processes, including detoxication of substrates such as plant allelochemicals, cuticle formation, pigmentation, and olfaction. Identification and characterization of Bombyx mori UGT genes could provide valuable basic information for this important family and explain the detoxication mechanism and other processes in insects. RESULTS: Taking advantage of the newly assembled genome sequence, we performed a genome-wide analysis of the candidate UGT family in the silkworm, B. mori. Based on UGT signature and their similarity to UGT homologs from other organisms, we identified 42 putative silkworm UGT genes. Most of them are clustered on the silkworm chromosomes, with two major clusters on chromosomes 7 and 28, respectively. The phylogenetic analysis of these identified 42 UGT protein sequences revealed five major groups. A comparison of the silkworm UGTs with homologs from other sequenced insect genomes indicated that some UGTs are silkworm-specific genes. The expression patterns of these candidate genes were investigated with known expressed sequence tags (ESTs), microarray data, and RT-PCR method. In total, 36 genes were expressed in tissues examined and showed different patterns of expression profile, indicating that these UGT genes might have different functions. CONCLUSION: B. mori possesses a largest insect UGT gene family characterized to date, including 42 genes. Phylogenetic analysis, genomic organization and expression profiles provide an overview for the silkworm UGTs and facilitate their functional studies in future.
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Project description:In holometabolous insects, the accumulation and utilization of storage proteins (SPs), including arylphorins and methionine-rich proteins, are critical for the insect metamorphosis. SPs function as amino acids reserves, which are synthesized in fat body, secreted into the larval hemolymph and taken up by fat body shortly before pupation. However, the detailed molecular mechanisms of digestion and utilization of SPs during development are largely unknown. Here, we report the crystal structure of Bombyx mori arylphorins at 2.8 Å, which displays a heterohexameric structural arrangement formed by trimerization of dimers comprising two structural similar arylphorins. Our limited proteolysis assay and microarray data strongly suggest that papain-like proteases are the major players for B. mori arylphorins digestion in vitro and in vivo. Consistent with the biochemical data, dozens of papain cleavage sites are mapped on the surface of the heterohexameric structure of B. mori arylphorins. Hence, our results provide the insightful information to understand the metamorphosis of holometabolous insects at molecular level.
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Project description:We characterized TRAS1, a retrotransposable element which was inserted into the telomeric repetitive sequence (CCTAA)n of the silkworm, Bombyx mori. The complete sequence of TRAS1, a stretch of 7.8 kb with a poly(A) tract at the 3' end, was determined. No long terminal repeat (LTR) was found at the termini of the element. TRAS1 contains gag- and pol-like open reading frames (ORFs) which are similar to those of non-LTR retrotransposons. The two ORFs overlap but are one nucleotide out of frame (+1 frameshift). Most of the approximately 250 copies of TRAS1 elements in the genome were highly conserved in the structure. Chromosomal in situ hybridization showed that TRAS1 elements are clustered at the telomeres of Bombyx chromosomes. A phylogenetic analysis using the amino acid sequence of the reverse transcriptase domain within the pol-like ORF revealed that TRAS1 falls into one lineage with R1, which is a family of non-LTR retrotransposons inserted into the same site within the 28S ribosomal DNA unit in most insects. TRAS1 may have been derived from R1 and changed the target specificity so that TRAS1 inserts into the telomeric repetitive sequence (CCTAA)n. Southern hybridization and Bal 31 exonuclease analyses showed that TRAS1 elements are clustered proximal to the terminal long tract of (CCTAA)n. TRAS1 is a novel family of non-LTR retrotransposons which are inserted into the telomeric repetitive sequences as target sites.
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Project description:Lepidoptera (butterflies and moths) is a major insect order including important pollinators and agricultural pests, however their microbiomes are little studied. Here, using next-generation sequencing (NGS)-based shotgun metagenomics, we characterize both the biodiversity and functional potential of gut microbiota of a lepidopteran model insect, the silkworm Bombyx mori. Two metagenomes, including the standard inbred strain Dazao (P50) and an improved hybrid strain Qiufeng?×?Baiyu (QB) widely used in commercial silk production, were generated, containing 45,505,084 and 69,127,002 raw reads, respectively. Taxonomic analysis revealed that a total of 663 bacterial species were identified in P50 silkworms, while 322 unique species in QB silkworms. Notably, Enterobacter, Acinetobacter and Enterococcus were dominated in both strains. The further functional annotation was performed by both BlastP and MG-RAST against various databases including Nr, COG, KEGG, CAZy and SignalP, which revealed?>5?×?106 protein-coding genes. These datasets not only provide first insights into all bacterial genes in silkworm guts, but also help to generate hypotheses for subsequently testing functional traits of gut microbiota in an important insect group.
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| S-EPMC2045683 | biostudies-literature
Project description:Three structurally related and novel antibacterial peptides have been isolated from the haemolymph of the silkworm, Bombyx mori, immunized with Escherichia coli. These peptides were 32 amino acids long and characteristically rich in proline residues. A unique threonine residue in each peptide was O-glycosylated and the modification seemed to be important for expression of antibacterial activity. The primary structure and antibacterial character of the novel peptides resemble those of abaecin (41% identity in amino acid sequence), an antibacterial peptide of the honeybee, although abaecin is not O-glycosylated. Incubation of the novel peptides with a liposome preparation caused leakage of entrapped glucose under low-ionic-strength conditions, suggesting that a target of the peptides is the bacterial membrane. We propose the name 'lebocin' for the novel peptide family isolated from B. mori.
| S-EPMC1135945 | biostudies-other