Transcriptional Activity at Supraoptimal Temperature of Growth in the Antarctic Psychrotrophic Bacterium Pseudomonas syringae

Abstract

Transcriptional activity was monitored in cells of the Antarctic psychrotrophic bacterium Pseudomonas syringae (Lz4W), which does not grow above 30 degrees C. It was observed that the bacterium was capable of synthesising RNA at a temperature range of 0-37 degrees C, both in vitro and in vivo. The net incorporation of the radioactive precursor, [3H]uridine, into RNA was found to be affected at 37 degrees C. A pulse-chase experiment following a 32P labeling of RNA in vivo indicated that the ribosomal RNAs (rRNAs) degrade faster at and above 30 degrees C. It was also found that the increased ribonuclease (RNase) activity at high temperature might be responsible for this degradation. The attack on ribosomal RNAs by RNase took place after their assembly into ribosomal particles. It is suggested that the degradation of rRNAs at supraoptimal temperatures might be a detrimental factor for growth above 30 degrees C.

Exoribonuclease R in Pseudomonas syringae Is Essential for Growth at Low Temperature and Plays a Novel Role in the 3′ End Processing of 16 and 5 S Ribosomal RNA

“…To the remaining 3 ml, rifampicin was added (final concentration, 400 g ml Ϫ1 ), and incubation was continued at 4°C for another 60 min. Total RNA was isolated from all the samples by hot phenol method (23), and the concentration of RNA was estimated by measuring the A 260 of all the samples. RNA (10 g) from each sample was resolved on 1.2% agarose gel (12) in Tris-acetate-EDTA buffer (20) and transferred to Hybond N ϩ membrane by vacuum transfer using 5ϫ salinated sodium citrate, 10 mM NaOH.…”

“…The cells in cultures at each time point were also examined microscopically (19) by staining them with Syto9 and propidium iodide (PI) using LIVE/DEAD Baclight bacterial viability kit (Molecular Probes, Eugene, OR). Isolation and Separation of Ribosome-Ribosomes were isolated and separated on sucrose gradient in presence of 10 mM or 0.3 mM MgCl 2 depending upon the experimental requirement as described earlier (23). Ribosomes were prepared either directly from 22°C grown cells or following their shift to low temperatures for different periods.…”

Re-examination of the taxonomic status of the AntarcticPseudomonas syringaeLz4W isolate and proposal to rename it as a novel speciesPseudomonas cryophilasp. nov

“…Morphologically, Lz4W T undergoes cell size variation, being reduced at low temperature (Regha et al , 2005) or in minimal growth medium (Sahu & Ray 2008). Biochemical and genetic studies with Lz4W T have established various cold-adaptive mechanisms that allow the Antarctic bacterium to sense and grow at low temperature (Ray et al ., 1994a, 1994b, 1994c, 1999; Uma et al ., 1999; Jagatap & Ray 1999; Janiyani & Ray, 2002; Seshukumar et al ., 2002; Regha et al ., 2005; Purusharth et al ., 2005, 2007; Satapathy et al ., 2008; Singh et al ., 2009; Pavankumar et al ., 2010; Sulthana et al ., 2011; Jagannadham & Chowdhury, 2012; Sinha et al , 2013; Kulkarni et al ., 2014). However, the taxonomic identification of Lz4W T as P. syringae species has remained ambiguous, as few key biochemical features of the strain reported earlier (Shivaji et al ., 1989) were found incorrect, and hence identification of this strain as P. syringae species was untenable (Cindy Morris, personal communication).…”

Molecular insights into the ecology of a psychrotolerant Pseudomonas syringae

“…In bacteria, RNA polymerase is a multi‐subunit complex (α2ββ'ω subunits), analysis of its individual components for cold adaptation has been difficult, hence, there is very little information available for psychrophilic bacterial RNA polymerases (Ernst et al ., 2018). The transcriptional activity and biochemical properties of RNA polymerases of P. syringae Lz4W, P. putida and P. aeruginosa were analysed and compared with those of mesophilic E. coli (Fujita and Amemura, 1992; Ray et al, 1999: Uma et al ., 1999; Afful et al ., 2019). Interestingly, P. syringae Lz4W RNA polymerase retained transcribing ability at 0°C as opposed to other Pseudomonas and E. coli RNA polymerases (Fujita and Amemura, 1992; Uma et al ., 1999; Afful et al ., 2019), suggesting RNA polymerase of P. syringae has evolved to function at low temperature, and hence contributes to the cold adaptation of the bacterium (Fig.…”