EC Number   |
General Information |
Reference |
|---|
   2.3.1.242 | malfunction |
constructed a chromosomal insertion mutation in lpxP, the structural gene for the transferase. Membranes from the lpxP mutant MKV11 grown at 12 °C lack the cold-induced palmitoleoyltransferase present in membranes of cold-shocked wild type cells but retain normal levels of the constitutive lauroyltransferase encoded by lpxL. When examined by mass spectrometry, about two-thirds of the lipid A molecules isolated from wild type Escherichia coli grown at 12 °C contain palmitoleate in place of laurate, whereas the lipid A of cold-adapted mutant MKV11 contain only laurate in amounts comparable with those seen in wild type cells grown at 30°C or above. To probe the integrity of the outer membrane, MKV11 and an isogenic wild type strain are grown at 30 or 12°C and then tested for their susceptibility to antibiotics. MKV11 exhibits a 10fold increase in sensitivity to rifampicin and vancomycin at 12°C compared with wild type cells but shows identical resistance when grown at 30°C. It is suggested that the palmitoleoyltransferase may confer a selective advantage upon Escherichia coli cells growing at lower temperatures by making the outer membrane a more effective barrier to harmful chemicals |
727837 |
| 2.3.1.242 | malfunction |
growth at 17°C is strongly reduced |
727343 |
| 2.3.1.242 | malfunction |
strains lacking lpxP fail to incorporate palmitoleate into their lipid A at 12°C but make normal amounts of hexa-acylated lipid A and are viable. MKV15, an Eschertichia coli lpxL lpxM lpxP triple mutant, that grows slowly on minimal medium at all temperatures but not on nutrient broth at any temperature. MKV15 synthesizes a lipid A molecule containing only the four primary (R)-3-hydroxymyristoyl chains. The outer membrane localization and content of lipid A are nearly normal in MKV15, as is the glycerophospholipid and membrane protein composition. However, the rate at which the tetra-acylated lipid A of MKV15 is exported to the outer membrane is reduced compared with wild type. The integrity of the outer membrane of MKV15 is compromised, as judged by antibiotic hypersensitivity, and MKV15 undergoes lysis following centrifugation. MKV15 may prove useful as a host strain for expressing late acyltransferase genes from other Gram-negative bacteria, facilitating the re-engineering of lipid A structure in living cells and the design of novel vaccines |
727838 |
| 2.3.1.242 | malfunction |
the flagellar regulon is downregulated in lpxP mutants, with a concomitant decrease in motility and downregulation of yplA expression |
-, 727617 |
| 2.3.1.242 | physiological function |
lipid A structures of lpxM and lpxP mutants lack the secondary lauroyl 12:0 group (R3'') or palmitoleoyl 16:1 group (R2''), respectively, and thus both represent a pentaacyl lipid A. Lipid A of Yersinia pestis lpxM/lpxP double mutant lacks both secondary acyl groups, 12:0 and 16:1, and is thus represented by the tetraacyl form. The absence of at least one acyl group is crucial for binding of lipopolysaccharide to toll-like receptor TLR4. Lipopolysaccharide from lpxM and and lpxP mutants induces TNF production at approximately the same level, the former being a slightly stronger activator than the latter |
-, 735652 |
| 2.3.1.242 | physiological function |
the enzyme is involved in lipid A acylation at low temperatures (21°C). The levels of expression of lpxP is higher at 21°C than at 37°C |
-, 727617 |
| 2.3.1.242 | physiological function |
the enzyme is involved in lipid synthesis at lower temperatures |
727343 |
| 2.3.1.242 | physiological function |
the enzyme is involved in the formation of a cold-adapted lipid A. It transfers palmitoleate from palmitoleoyl-[acyl-carrier protein] to Kdo2-lipid IVA, which is also the acceptor for the lpxL-encoded lauroyl transferase. Palmitoleate is not present in lipid A isolated from Escherichia coli grown at 30°C or higher, but it comprises about 11% of the fatty acyl chains of lipid A in cells grown at 12 °C. The appearance of palmitoleate at 12°C is accompanied by a decline in laurate from 18% to 5.5%. The palmitoleoyl transferase is induced more than 30fold upon cold shock. The replacement of laurate with palmitoleate in lipid A may reflect the desirability of maintaining the optimal outer membrane fluidity at 12°C |
727828 |
