Kinase Family PTF
Kinase Classification: Group AGC: Kinase Family PTF
Phototrophin and Flippase kinases is a new family, defined in Sep 2010, which includes a subfamily of kinases that phosphorylate phospholipid flippases in yeast, with homologs in other fungi, Giardia and Naegleria, and an expanded family of plant kinases that include the phototrophin blue light receptors. These were both classified as unclassified RSK kinases, and they retain substantial similarity to RSKs. Both phototrophins and flippase kinases are associated with the plasma membrane.
The FPK family is defined by a pair of yeast kinases, FPK1 and FPK2 (YNR047W and KIN82), which were shown [1] to phosphorylate and control several 'flippases', enzymes which regulate the asymmetric distribution of phospholipids on the two sides (leaflets) of the plasma and Golgi membranes. FPK1 is in turn phosphorylated and downregulated by the Akt/SGK kinases YPK1/YPK2 [2].
The Neurospora crassa FPK, nrc-2 was isolated in a screen for defects in conidiation [3]. Mutations repress vegetative hyphae and result in female sterility. A recent thesis (Andrew Greene) shows that nrc-2 has a circadian rhythm and may be a metabolic activity sensor for the circadian oscillator. Neurospora has a blue-light receptor, wc-1, which is related to plant phototrophins but lacks a kinase domain, and this may be within the same pathway as nrc-2. Some conidiation genes are also sensitive to blue light [4].
The phototrophins are found in green plants, and consist of several light-sensing PAS domains (aka LOV - light, oxygen and voltage receptors), fused to the protein kinase domain. Similar PAS domains are seen in the aureochrome genes of stramenopiles (including seaweed) and in bacteria and are often fused to histidine kinases, so it appears that the histidine kinase was replaced by an ePK domain in green plants.
The fpk1 gene of Fusarium verticillioides is a PKA, not a PTF kinase.
References
- Nakano K, Yamamoto T, Kishimoto T, Noji T, and Tanaka K. Protein kinases Fpk1p and Fpk2p are novel regulators of phospholipid asymmetry. Mol Biol Cell. 2008 Apr;19(4):1783-97. DOI:10.1091/mbc.e07-07-0646 |
- Roelants FM, Baltz AG, Trott AE, Fereres S, and Thorner J. A protein kinase network regulates the function of aminophospholipid flippases. Proc Natl Acad Sci U S A. 2010 Jan 5;107(1):34-9. DOI:10.1073/pnas.0912497106 |
- Kothe GO and Free SJ. The isolation and characterization of nrc-1 and nrc-2, two genes encoding protein kinases that control growth and development in Neurospora crassa. Genetics. 1998 May;149(1):117-30. DOI:10.1093/genetics/149.1.117 |
- Lauter FR and Russo VE. Blue light induction of conidiation-specific genes in Neurospora crassa. Nucleic Acids Res. 1991 Dec 25;19(24):6883-6. DOI:10.1093/nar/19.24.6883 |
Gerard 06:40, 19 September 2010 (PDT)
