Acanthamoeba castellanii STAT protein.

Jay Reddy,Jacek Leluk,Anna Kicinska,Wieslawa Jarmuszkiewicz

doi:10.1371/journal.pone.0111345

Abstract

STAT (signal transducers and activators of transcription) proteins are one of the important mediators of phosphotyrosine-regulated signaling in metazoan cells. We described the presence of STAT protein in a unicellular, free-living amoebae with a simple life cycle, Acanthamoeba castellanii. A. castellanii is the only, studied to date, Amoebozoan that does not belong to Mycetozoa but possesses STATs. A sequence of the A. castellanii STAT protein includes domains similar to those of the Dictyostelium STAT proteins: a coiled coil (characteristic for Dictyostelium STAT coiled coil), a STAT DNA-binding domain and a Src-homology domain. The search for protein sequences homologous to A. castellanii STAT revealed 17 additional sequences from lower eukaryotes. Interestingly, all of these sequences come from Amoebozoa organisms that belong to either Mycetozoa (slime molds) or Centramoebida. We showed that there are four separated clades within the slime mold STAT proteins. The A. castellanii STAT protein branches next to a group of STATc proteins from Mycetozoa. We also demonstrate that Amoebozoa form a distinct monophyletic lineage within the STAT protein world that is well separated from the other groups.

Highlights

In mammals, seven signal transducer and activator of transcription proteins (STATs), i.e., STAT1–4, STAT5a, STAT5b and STAT6, have been identified [1]
A. castellanii STAT Sequencing The A. castellanii STAT DNA sequence was assembled after amplification of 59 and 39 fragments using RACE and cDNA from cells from the early exponential phase of growth
The similarity search using this nucleotide sequence showed a homology with fragments of two other A. castellanii sequences (67% and 66% identity), which are predicted to be STAT proteins (XM_004352905 and XM_004339187) [30]

Summary

Introduction

Seven signal transducer and activator of transcription proteins (STATs), i.e., STAT1–4, STAT5a, STAT5b and STAT6, have been identified [1]. A. castellanii seems to be a unique unicellular organism with a simple life cycle that possesses STAT proteins. We described the results of a careful search among the STAT protein coding sequences of other lower eukaryotes.

Results

Conclusion