LPXK (At3g20480, Q8LEA0) notes
Deep research could not be run in this environment (provider auth failure); notes are from the cached
full text of Li et al. 2011 (PMID:21709257, PMC3136250), the UniProt record and PubMed searches.
Identity
- Single-copy Arabidopsis ortholog of E. coli LpxK (tetraacyldisaccharide 4'-kinase, EC 2.7.1.130;
Pfam PF02606, InterPro IPR003758, PANTHER PTHR42724:SF1), 26% identity to E. coli LpxK
PMID:21709257.
- UniProt: predicted mitochondrial transit peptide 1..32; "Belongs to the LpxK family"; the P-loop
ATP-binding motif of LpxK is the basis of the ATP binding IEA.
Genetics and lipid chemistry (Li et al. 2011)
- Alleles atlpxk-1 (SALK_063783C), atlpxk-2 (SALK_100275C), atlpxk-3 (SALK_145083), Col-0; null mutants
viable, no visible phenotype.
- Substrate accumulation: the LpxK substrate disaccharide 1-phosphate (DS-1-P) accumulates in atlpxk-1
(and in atkdta-1) but is undetectable in wild type PMID:21709257.
- Lipid X modestly up PMID:21709257.
- The LpxK product lipid IVA is detected only in kdta mutants, i.e. it is made in lpxk+ plants and
consumed by KdtA PMID:21709257.
- Independent alleles agree PMID:21709257.
- No in vitro kinase assay or complementation reported for AtLpxK.
Localization
- 5'-terminal GFP fusion mitochondrial; full-length fusion too dim PMID:21709257. Caveat: the 5' fusion shows the targeting signal is mitochondrial,
not where the mature full-length enzyme sits within mitochondria.
Curation decisions
- GO:2001289 lipid X metabolic process is obsolete (QuickGO confirms; no replacement). LPXK does not
act on lipid X; the IMP (lipid X rise) is an indirect pathway effect. MODIFY to GO:0009245 lipid A
biosynthetic process, which is also supported directly by DS-1-P accumulation.
- No NEW rows: all supported terms are already in GOA (kinase activity IMP, mitochondrion IDA, lipid A
biosynthetic process IEA); experimental evidence placed in those rows.
- RAR (PMID:32470107) flagged the plant lipid A family of annotations; refuted for this pathway.