In relation to cellular processes and signaling, thirteen proteins were identified in categories D, T, O, M and N (Table 1). Two of these proteins are known to be correlated with heat tolerance, DnaK and GroEL molecular chaperones [12, 25]. Two proteins also found in this group were thioredoxin TrxA and bacterioferritin comigratory proteins (Bcp), which have been characterized as oxidative-stress responsive. Still considering the COG classification, thirteen induced proteins comprised a set related to information storage and processing (Table 1), including transcription PD-1/PD-L1 Inhibitor 3 regulators and translation factors. The translation factors can act as chaperones in response to heat stress, and more details

of this function are discussed below. CA4P chemical structure Interesting was also the differential expression

of VirD4, a TraG-like protein that plays an important role in conjugative transfer showing high similarity to Agrobacterium, and also reported in the draft genome of strain PRF 81 [13]. The transcription of the vir regulon in Agrobacterium tumefaciens is induced by specific plant-phenolic compounds, but also by several other abiotic stimuli, such as low pH and temperatures below 30°C [26]. VirD4 acts in the translocation of effectors proteins and has been associated with different plant-bacterium interactions, both pathogenic and symbiotic. Also, VirD4 acts in couple DNA processing and transference by conjugation mechanism. Therefore, this protein has a broader role than the action in type IV secretion system. An association between heat stress and type IV secretion system 4SC-202 components was described by Zahri et al.[27], since the expression of type IV secretion system in a modified E. coli induced heat shock genes. Differential expression of the two-component response regulators (NtrX and ChvI) Two-component systems are composed by a sensor kinase protein that transmits the environmental stimulus to a response regulator protein via phosphorylation. The phosphorylated regulator

modulates the expression of the target genes required for the appropriate changes, mediating rapid metabolic responses for adaptation to new conditions [28]. Interestingly, these two up-regulated proteins BCKDHA in our study (NtrX and ChvI) are the response-regulator components. NtrX has also been found to be expressed in Gluconacetobacter diazotrophicus[29], Sinorhizobium (=Ensifer) meliloti[30], and Mesorhizobium loti[31]. This protein is recognized to be involved in N metabolism and nitrogen fixation, probably acting as a transcriptional activator of genes related to nitrate metabolism [32, 33]. The second two-component system, ChvI, characterized in several bacteria such as S. meliloti[34] and A. tumefaciens[35], acts in translation regulation of enzymes related to the biosynthesis of the succinoglycan exopolysaccharide (EPSI). In addition to this role, this two-component system signaling is critical for the viability of free-living S.