Sequencing and Expression Analysis of the Gene Encoding PII Signal Protein in Chlorella Variabilis NC64A

Ekaterina Minaeva Elena Ermilova

doi:10.4172/2329-9029.1000142

Abstract

Although PII signal transduction proteins have been described in bacteria, archaea and plants, only one PII homolog has so far been characterized in green algae. Using a specific antibody to the PII protein from Chlamydomonas (CrPII), we provide the evidence that the model plant organism Chlorella variabilis NC64A (NC64A) possesses a protein that is immunologically related to the CrPII. The coding region of the CvGLB1 gene was sequenced, and it contained six introns and seven exons. In comparison to PII proteins from plants and cyanobacteria, the predicted amino acid sequence showed its highest degree of identity with proteins from Chlamydomonas (55.2%) and cyanobacteria, Synechococcus PCC 7942 (52.3%) and Synechocystis sp PCC 6803 (51.8%). Here, we demonstrated that like its plant PII homologs, the C. variabilis PII protein (CvPII) is appeared to be localized in the chloroplast. Expression analysis indicated that CvGLB1 transcription was independent on growth rates or nitrogen availability. The results of this study will facilitate not only characterization of PII signaling network but also the transcriptional analysis in this alga.

Highlights

PII signal transduction proteins constitute an abundant protein family, present in bacteria, archaea and plants [1,2,3,4]
Expression analysis of C. variabilis PII protein (CvPII) under various nitrogen conditions: To test the expression patterns of CvGLB1 gene, we carried out a comparative qRT-PCR analysis on cells in exponential and stationary phases of culture grown on MBBM, arginine- and ammonium-supplemented media
Our results provide crucial information for sequence and transcriptional analysis of CvGLB1 gene encoding PII in C. variabilis NC64A, which constitutes an excellent model system for the study of all aspects of plant physiology, including the molecular mechanisms underlying regulation of metabolism

Summary

Introduction

PII signal transduction proteins constitute an abundant protein family, present in bacteria, archaea and plants [1,2,3,4]. PII proteins control different metabolic pathways and their regulatory functions in most bacteria involve various posttranslational modifications [2]. These proteins can be regarded as signal integrators, whereby the various signals are integrated by the inter-conversion of different PII states. To study fundamental problems in plant physiology, another unicellular green alga, Chlorella variabilis NC64A, has been recognized as the excellent model organism [9]. For this reason, we started studying PII protein in C. variabilis NC64A. This is the first report to evaluate reference gene for the transcriptional analysis of algae of the Chlorella genus

Materials and Methods

Results and Discussion

Conclusion