Expression of ABC transporters negatively correlates with ectoine biosynthesis in Halomonas campaniensis under NaCl and ultraviolet mutagenesis treatments revealed by transcriptomic and proteomics combined analysis

Halomonas species are renowned for their production of organic compatible solutes, particularly ectoine. However, the identification of key regulatory genes governing ectoine production in Halomonas remains limited. In this study, we conducted a combined transcriptome-proteome analysis to unveil additional regulatory genes influencing ectoine biosynthesis, particularly under ultraviolet (UV) and salt conditions. NaCl induction resulted in a 20-fold increase, while UV treatment led to at least 2.5-fold increases in ectoine production. The number of overlapping genes between transcriptomic and proteomic analyses for three comparisons, i.e., non-UV with NaCl (UV0-NaCl) vs. non-UV without NaCl (UV0), UV strain 1 (UV1-NaCl) vs. UV0-NaCl, and UV strain 2 (UV2-NaCl) vs. UV0-NaCl were 137, 19, and 21, respectively. The overlapped Gene Ontology (GO) enrichments between transcriptomic and proteomic analyses include ATPase-coupled organic phosphonate, phosphonate transmembrane transporter activity, and ATP-binding cassette (ABC) transport complex in different comparisons. Furthermore, five common genes exhibited different expression patterns at mRNA and protein levels across the three comparisons. These genes included orf01280, orf00986, orf01283, orf01282 and orf01284. qPCR verification confirmed that three of the five common genes were notably under-expressed following NaCl and UV treatments. This study highlighted the potential role of these five common genes in regulating ectoine production in Halomonas strains.