Journal of Proteome Research ARTICLE Figure 2. Venn-diagram of (A) transcriptomic and (B) proteomic proﬁling bioﬁlm response between Sulfolobus strains. Up- and down regulated genes and proteins were analyzed by BLASTp in order to identify common bioﬁlm-regulated changes at the transcriptomic and proteomic level. The number of homologous genes and protein between the Sulfolobus species are indicated by numbers. stress-related proteins, that is, a thioredoxin (Saci_1823 and SSO2232) and a peroxiredoxin (Saci_2227 and SSO2613), while S. tokodaii showed increased levels of a bacterioferritin comigratory protein-like, belonging to the peroxiredoxins family proteins.33 As is well-known, peroxiredoxins are ubiquitous proteins that catalyze the reduction of hydroperoxides, which undertake the thiol- dependent reduction of peroxide substrates, thus conferring resis- tance to oxidative stress.33 The DNA-binding protein Sul7d (Saci_0064, SSO10610 and STS007) also exhibited altered expression patterns in all three Sulfolobus species in bioﬁlm-grown populations. Sul7d has been intensely studied in S. acidocaldarius and S. solfataricus, and it is described as an archaeal histone-like protein that binds nonspeciﬁcally to DNA inducing negative supercoiling (Baumeister et al.34). From our BLASTp analyses, we identiﬁed a putative transcrip- tional regulator Lrs14-like that was upregulated in bioﬁlms of all three species (Saci_1223, SSO1101 and ST0837) (Table 2). These putative proteins are homologous to the Lrs14 protein (SSO1108) of S. solfataricus, the protein levels of which were also increased during the bioﬁlm lifestyle (Table 3). Thus, the expression of these homologous transcriptional regulators might constitute a key regulatory factor involved in Sulfolobus bioﬁlm development. Additionally, the expression of some other genes 4114 dx.doi.org/10.1021/pr2003006 |J. Proteome Res. 2011, 10, 4105–4119