Disease relevance of pepN

• The complete nucleotide sequence has been determined for the pepN gene of Escherichia coli K-12 [1].
• Three out of five clones were identified to express the Lactobacillus pepN gene; the others were shown to express a second aminopeptidase gene, designated pepL [2].
• By analogy with Salmonella typhimurium this locus has been called pepN (Miller, 1975) [3].
• The chromosomal pepN gene encoding lysyl-aminopeptidase activity in Lactococcus lactis has been identified in a lambda EMBL3 library in Escherichia coli by using an immunological screening with antiserum against a purified aminopeptidase fraction [4].
• In susceptible lepidopteran insects, aminopeptidase N and cadherin-like proteins are the putative receptors for Bacillus thuringiensis (Bt) toxins [5].

High impact information on pepN

• Aminopeptidase N from Escherichia coli is a major metalloprotease that participates in the controlled hydrolysis of peptides in the proteolytic pathway [6].
• Structure of aminopeptidase N from Escherichia coli suggests a compartmentalized, gated active site [6].
• Crystal Structure of Aminopeptidase N (Proteobacteria Alanyl Aminopeptidase) from Escherichia coli and Conformational Change of Methionine 260 Involved in Substrate Recognition [7].
• The open reading frame encodes a 649-amino acid protein with a theoretical molecular mass of 72,545 Da and bears the consensus sequence of the zinc metalloexopeptidases, indicating that the enzyme belongs to this family, which includes aminopeptidase A, aminopeptidase N, and leukotriene-A4 hydrolase [8].
• Its position on the E. coli chromosome was determined at 20.8 min between the asnS and pepN loci [9].

Chemical compound and disease context of pepN

• Using the chromogenic substrate leucine-beta-naphthylamide (Leu-NH-Nap) and E. coli strain CM89 lacking the corresponding enzyme activity in an enzymic plate assay, allowed the isolation of two peptidase genes; the newly described pepL and the recently cloned and sequenced pepN [2].
• Phosphinate, sulfonate, and sulfonamidate dipeptides as potential inhibitors of Escherichia coli aminopeptidase N [10].
• A recombinant form of aminopeptidase N (molecular weight 99 kDa) from Escherichia coli was crystallized by the hanging-drop vapour-diffusion method using ammonium sulfate as a precipitating agent [11].

Biological context of pepN

• The nucleotide sequence of the pepN gene and its over-expression in Escherichia coli [1].
• In the process of subcloning the pepN gene we constructed a plasmid which causes peptidase N to be produced at a level of 50% of total protein [1].
• The pepN locus lay between ompF and asnS at approximately 20.8 min on the E. coli chromosome [12].
• The N-terminal amino acid sequence deduced from the pepN nt sequence corresponds to the N-terminal sequence of the purified protein; the amino acid composition of the protein is also in good agreement with that deduced from the gene sequence [13].
• The transcriptional level of regulation can be deduced from the observation of these effects in strains carrying operon fusion pepN-lacZ [14].

Anatomical context of pepN

• Investigation of the type of interactions of aminopeptidase N with the plasma membrane only revealed that aminopeptidase N has mainly an electrostatic interaction with the outer surface, probably mediated by magnesium ion bridges [15].
• As well, N-ethylmaleimide (0.4 mM), under conditions which do not allow penetration in the cytoplasm, caused 70% inhibition of aminopeptidase N. Binding of 125I-labeled antiaminopeptidase N antibody to spheroplasts (from K12 strain) was used to assay the orientation of aminopeptidase N in the membrane [15].

Associations of pepN with chemical compounds

• The NH2-terminal region of aminopeptidase N does not contain any fragment resembling signal sequence and the protein is not produced in a precursor form [16].
• Amino acid sequence analysis of the pepN gene translation product shows high homology with other PepN enzymes from lactic acid bacteria and exhibits the signature sequence of the zinc metallopeptidase family [17].
• Starting with a pepN pepA pepD strain, selection for resistance to L-valyl-glycyl-glycine or several other valine peptides produced mutants deficient in another aminopeptidase, peptidase B. Mutants resistant to L-valyl-L-proline lack peptidase Q, an activity capable of rapid hydrolysis of X-proline dipeptides [18].
• Mutants altered in their expression of the hybrid pepN-lacZ gene have been selected for resistance to p-nitrophenyl-beta-D-thiogalactopyranoside (a bacteriostatic compound that enters the cells via lac permease) [19].
• Neither mutant cells which were devoid of aminopeptidase N activity nor parental strains with the enzyme activity inhibited with phenylmercuric chloride contained the characteristic black caps [15].

Other interactions of pepN

• The nucleotide sequence of the region probably responsible for regulation of pepN expression and of the region encoding the amino-terminal part of aminopeptidase N, has been determined [16].
• AIMS: To clone and analyse seven putative promoter fragments (pepC, pepN, pepX, pepO, pepE, pepO2, hsp17) from Lactobacillus helveticus CNRZ32 for their expression in Lact. helveticus CNRZ32, Lact. casei ATCC334 and Lactococcus lactis MG1363 [20].
• Deletion of the apeA gene, either with or without deletion of other proteinases (protease IV and aminopeptidase N), did not have any effect on cell growth in the various media tested [21].

Analytical, diagnostic and therapeutic context of pepN

• By restriction mapping, we identified and subcloned the 5' region of the pepN gene and then determined its nucleotide sequence [22].
• By using synthetic primers and a battery of PCR techniques, the pepN gene was amplified, subcloned, and further sequenced, revealing an open reading frame of 2,541 nucleotides encoding a protein of 847 amino acids with a molecular weight of 96,252 [17].
• The B. melitensis pepN gene was cloned, expressed in Escherichia coli and purified by affinity chromatography [23].
• The microvillar membrane enzymes alkaline phosphatase, aminopeptidase N and alpha-glucosidase were released into the culture medium during organ culture, and this process was significantly enhanced by enteropathogenic E coli [24].
• Sequence analysis, distribution and expression of an aminopeptidase N-encoding gene from Lactobacillus helveticus CNRZ32 [25].

References