Transition of nearest neighbour spacing distribution and gene co-expression network from S. oneidensis microarray profiles. (A) The normalized NNSDs of correlation matrices of S. oneidensis heat/cold shock gene expressions at different cutoff values. They were plotted against the curves of Wigner surmise (navy) and Poisson distribution (red). The x-axis is the level spacing s and the y-axis is the probability of NNSDs. (B) A node representing a hypothetic protein SO2017 is interconnected to many heat shock proteins, suggesting a possible role in heat shock. The heat shock proteins are grpE, lon, SO3681, dnaJ, dnaK, groES, groEL, prlC and hslV. (C) Growth curves of SO2017 deletion mutant and its parental strain DSP10. Both strains were initially grown in LB media and shifted to 42°C when OD600 reached 0.69 and 0.62, respectively. In an independent experiment, the viability of the ΔSO2017 strain was reduced by 46% at 10 min after exposure to 42°C (data not shown).