Functional conservation of cold shock domains in bacteria and higher plants

Abstract

In Escherichia coli, a family of cold shock proteins (CSPs) function as transcription antiterminators or translational enhancers at low temperature by destabilizing RNA secondary structure. A wheat nucleic acid-binding protein (WCSP1) was found to contain a cold shock domain (CSD) bearing high similarity to E. coli cold shock proteins. In the present study, a series of mutations were introduced into WCSP1, and its functionality was investigated by using in vivo and in vitro assays in the context of functional conservation with E. coli CSPs. Constitutive expression of WT WCSP1 in an E. coli cspA, cspB, cspE, cspG quadruple deletion mutant complemented its cold-sensitive phenotype, suggesting that WCSP1 shares a function with E. coli CSPs for cold adaptation. In addition, transcription antitermination activity was demonstrated for WCSP1 by using an E. coli strain that has a hairpin loop upstream of a chloramphenicol resistance gene. In vitro dsDNA melting assays clearly demonstrated that WCSP1 melts dsDNA, an activity that was positively correlated to the ability to bind ssDNA. When mutations were introduced at critical residues within the consensus RNA binding motifs (RNP1 and RNP2) of WCSP1, it failed to melt dsDNA. Studies with WCSP1-GFP fusion proteins documented patterns that are consistent with ER and nuclear localization. In vivo and in vitro functional analyses, coupled with subcellular localization data, suggest that WCSP1 may function as a RNA chaperone to destabilize secondary structure and is involved in the regulation of translation under low temperature.cold acclimation ͉ cold shock protein ͉ RNA binding ͉ RNA chaperone ͉ wheat

Advances in physiological and molecular aspects of plant cold tolerance

“…The expression of CspA and CspB in transgenic rice improved the growth of plants under the effect of a number of abiotic factors like cold, heat and water deficit. The expression of bacterial CSPs increased cold tolerance in transgenic Arabidopsis (Karlson & Imai 2003;Nakaminami et al 2006;Castiglioni et al 2008). Some PR (pathogenrelated) proteins such as PR1, PR2, PR5, PR10, PR11 and PR14 are approved to be up-regulated by low-temperature treatment (Seo et al 2008;Zhang et al 2010).…”

Comparison of structure, function and regulation of plant cold shock domain proteins to bacterial and animal cold shock domain proteins

“…WCSP1 complements the cold sensitive phenotype of the quadruple Csp-deletion strain of E. coli (BX04), indicating that this protein can function as an RNA chaperone in vivo in a bacterial system (30). Expression studies revealed that some Arabidopsis CSP transcripts are also increased upon cold stress treatment, indicating a potential role in cold adaptation (19,31,32).…”

“…In the case of plant CSPs, no evidence has been produced to suggest that they may function to directly affect transcription. However, CSPs from wheat and Arabidopsis are localized to the nucleus (30,(32)(33)(34)53), which indirectly supports a putative functional role related to transcription.…”

Respuesta transcripcional de Populus a bifenilos policlorados: Aspectos aplicados a la fitorremediación

“…Las proteínas Yb-1 se unen a la secuencia Yb-1 invertida CCATT (ATTGG) y activan el gen MDR1 que codifica un transportador ABC (ATP-Binding Cassette), que actúa expulsando de las células los compuestos que les resultan tóxicos (por ejemplo, los compuestos antitumorales). En pacientes de cáncer siempre se comprueba si se está sintetizando esta proteína ya que su expresión en células cancerígenas es un indicador de resistencia a tratamientos antitumorales (Nakaminami, 2006). Sin embargo, en herbáceas, esta familia nunca ha sido asociada en respuesta a xenobióticos.…”

“…Las regiones ricas en glicina y los dedos de zinc CCHC están implicados en la unión a ácidos nucléicos y a la unión a otras proteínas (Karlson et al, 2002;Nakaminami et al, 2006;Sasaki et al, 2007). La mayoría de los estudios de esta familia se han centrado a la caracterización de proteínas CSP de bacterias y animales, existiendo en la actualidad poca información sobre de las proteínas CSP en plantas.…”