Disease relevance of lspA

• In genetic complementation, recombinant lspA from R. typhi significantly restores the growth of temperature-sensitive E. coli Y815 at the nonpermissive temperature, supporting its biological activity as SPase II in prolipoprotein processing [1].
• The lspA Gene, Encoding the Type II Signal Peptidase of Rickettsia typhi: Transcriptional and Functional Analysis [1].
• Here, we describe the analysis of lspA, encoding a putative SPase II, an essential component of lipoprotein processing in gram-negative bacteria, from Rickettsia typhi [1].
• The importance of the 15 best conserved residues in these domains was investigated using the type II SPase of Bacillus subtilis, which, unlike SPase II of Escherichia coli, is not essential for viability [2].
• To explore further the importance of lipoprotein processing in Gram-positive eubacteria, an SPase II mutant strain of Lactococcus lactis was constructed [3].

High impact information on lspA

• These results indicate that the prolipoprotein signal peptidase requires a glyceride modified cysteine residue at the cleavage site [4].
• The deduced amino acid sequence indicates that prolipoprotein signal peptidase contains 164 residues [5].
• The nucleotide sequence of the prolipoprotein signal peptidase (lsp) gene has been determined [5].
• Only Asp-14 was required for stability of SPase II, indicating that the other five residues are required for catalysis, the active site geometry, or the specific recognition of lipid-modified preproteins [2].
• Here we experimentally verify this prediction by metabolic labeling of subunit b with [14C]palmitic acid and by in vivo interfering with the processing of the prolipoprotein form of subunit b by the antibiotic globomycin, a specific inhibitor of the signal peptidase II [6].

Chemical compound and disease context of lspA

• Prolipoprotein signal peptidase of Escherichia coli requires a cysteine residue at the cleavage site [4].
• This new cleavage was resistant to globomycin, an inhibitor of the prolipoprotein signal peptidase of Escherichia coli [7].
• Both non-mutant and mutant signal peptides appeared to be removed at the same unique site between cysteine 21 and serine 22, one residue from the E. coli signal peptidase II processing site [8].
• Globomycin, an inhibitor of lipoprotein-specific signal peptidase II, was lethal for E. coli only when Lpp possessed the C-terminal lysine [9].
• A nonessential signal peptidase II (Lsp) of Myxococcus xanthus might be involved in biosynthesis of the polyketide antibiotic TA [10].

Biological context of lspA

• The higher transcriptional level of all three genes at the preinfection time point indicates that only live and metabolically active rickettsiae are capable of infection and inducing host cell phagocytosis. lspA and lgt, which are involved in lipoprotein processing, show similar levels of expression [1].
• Complementation analysis with plasmids carrying various DNA fragments derived from pLC3-13 showed that the lspA locus is between the rpsT and ileS loci [11].
• To define the boundaries of the operon, we applied Northern blotting hybridization and mRNA 5'-end mapping to analyze mRNA from a wild-type strain (SM31) and a mutant strain (SM31-2B4) that exhibits an increased expression of prolipoprotein signal peptidase [12].
• The presence of a signal sequence of 22 amino acids with a consensus sequence for cleavage by signal peptidase II indicates that the antigen is a lipoprotein, and striking similarity with peptidoglycan-associated lipoproteins (PALs) from E. coli (51% amino acid homology) and Haemophilus influenzae (55% homology) is noted [13].
• Analysis of the predicted amino acid sequence showed a characteristic signal peptidase II cleavage site, and the presence of the acylation site was confirmed by identification of a lipid-associated membrane protein, similar in molecular mass to MSPB, in [3H]palmitate-labelled membrane proteins [14].

Anatomical context of lspA

• The inverted plasma membrane vesicles used here must therefore contain active lipid-modifying enzymes and signal peptidase II [15].

Associations of lspA with chemical compounds

• Inhibition of prolipoprotein signal peptidase by globomycin [16].
• This new cleavage between alanine and lysine residues was resistant to globomycin, a specific inhibitor for signal peptidase II [17].
• This prolipoprotein signal peptidase has a pH optimum at 6.0, is not inhibited by EDTA, and requires 1 mM dithiothreitol for stability [18].
• The molecular weight of prolipoprotein signal peptidase was estimated to be approximately 18,000 by its mobility on polyacrylamide gel electrophoresis and was found to be the same as that of SPase II purified from the wild-type cells [19].
• It is believed that the lipoprotein signal peptidase directly cleaves the lipoprotein signal peptide at the peptide bond between the glycine residue at position 20 and the cysteine residue at position 21 of the prolipoprotein [20].

Other interactions of lspA

• Sequencing of tagA revealed the presence of an open reading frame (ORF) of 568 amino acids with a characteristic signal peptidase II cleavage site at the N terminus [21].

Analytical, diagnostic and therapeutic context of lspA

• Sequence analysis of the pG gene revealed an open reading frame encoding a putative lipoprotein of 196 amino acids with a calculated molecular mass of 22 kDa and a consensus cleavage sequence (Leu-X-Y-Z-Cys) recognized by signal peptidase II [22].

References