Fig. 3: The ArcZ sRNA is a conserved regulator of multiple HMV-related genes.

a Genomic context of the arcZ gene in K. pneumoniae. b Multiple sequence alignment of ArcZ sRNA. KPN K. pneumoniae, ECO E. coli, STM S. Typhimurium, CRO Citrobacter rodentium, ENT Enterobacter spp., SMA Serratia marcescens, YPE Yersinia pestis, PLU Photorhabdus luminescens. The scissors indicate RNase E cleavage site and start of mature ArcZ. c HMV is regulated by ΔarcZ and a chromosomal complementation of ArcZ. A copy of arcZ gene with its own promoter was inserted into putA locus by homologous recombination. The i-wza mutant serves as negative control. N = 3 biological replicates, bars indicate mean ± SD. **: p < 0.01; two-tailed Student’s t-test. d ArcZ inhibits the production of capsular polysaccharides. The i-wza mutant serves as the acapsular control sample. N = 3 biological replicates, bars indicate mean ± SD. *: p < 0.05, **: p < 0.01; two-tailed Student’s t-test. e Circos plot highlighting the ArcZ interactome. Interactions involving known capsule and HMV-related genes are highlighted in dark blue, tested genes in boldface. The number of S-chimeras are shown in brackets. f Regulation of putative target genes by ArcZ. Fluorescence was determined in cells containing translational sfGFP reporters. N = 3 biological replicates, bars indicate mean ± SD. *: p < 0.05, **: p < 0.01, ns: not-significant; two-tailed Student’s t test. g, h HMV assay for the mlaA and fbp mutants. The acapsular i-wza mutant served as non-mucoid control. N = 3 biological replicates, bars indicate mean ± SD. *: p < 0.05, **: p < 0.01; two-tailed Student’s t-test. i, j Western blot analysis of MlaA and Fbp protein levels, respectively. GroEL served as loading control. The images are representative of three independent experiments. Uncropped blots in Source Data. k, l Western blot analysis of MlaA and Fbp proteins upon ArcZ overexpression. Cultures were supplemented with 1 mM IPTG to induce ArcZ overexpression. ArcZ containing 2 nt (M2) or 5 nt (M5) mutations (a) were included. The images are representative of three independent experiments. Uncropped blots in Source Data.