3PTJ: Structural And Functional Analysis Of Arabidopsis Thaliana Thylakoid Lumen Protein Attlp18.3

The membrane protein AtTLP18.3 of Arabidopsis (Arabidopsis thaliana) contains a domain of unknown function, DUF477; it forms a polysome with photosynthetic apparatuses in the thylakoid lumen. To explore the molecular function of AtTLP18.3, we resolved its crystal structures with residues 83 to 260, the DUF477 only, and performed a series of biochemical analyses to discover its function. The gene expression of AtTLP18.3 followed a circadian rhythm. X-ray crystallography revealed the folding of AtTLP18.3 as a three-layer sandwich with three alpha-helices in the upper layer, four beta-sheets in the middle layer, and two alpha-helices in the lower layer, which resembles a Rossmann fold. Structural comparison suggested that AtTLP18.3 might be a phosphatase. The enzymatic activity of AtTLP18.3 was further confirmed by phosphatase assay with various substrates (e.g. p-nitrophenyl phosphate, 6,8-difluoro-4-methylumbelliferyl phosphate, O-phospho-L-serine, and several synthetic phosphopeptides). Furthermore, we obtained the structure of AtTLP18.3 in complex with O-phospho-L-serine to identify the binding site of AtTLP18.3. Our structural and biochemical studies revealed that AtTLP18.3 has the molecular function of a novel acid phosphatase in the thylakoid lumen. DUF477 is accordingly renamed the thylakoid acid phosphatase domain.
PDB ID: 3PTJDownload
MMDB ID: 94603
PDB Deposition Date: 2010/12/3
Updated in MMDB: 2014/11
Experimental Method:
x-ray diffraction
Resolution: 2.6  Å
Source Organism:
Similar Structures:
Biological Unit for 3PTJ: monomeric; determined by author and by software (PISA)
Molecular Components in 3PTJ
Label Count Molecule
Protein (1 molecule)
Upf0603 Protein At1g54780, Chloroplastic(Gene symbol: TLP18.3)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB