The Gly115Arg mutation present in strains of D was not predicted to result in enzyme inactivation based on sequence analysis alone, making it unclear whether AaxB sequence variations seen in other Chlamydia alter AaxB activity. To further our understanding of this enzyme and determine whether the inactivation selleck chemicals of AaxB is restricted to the human-specific C. trachomatis serovars, we completed an activity panel using variant Chlamydia AaxB proteins in a surrogate E. coli acid shock assay. A pan-chlamydial
anti-AaxB antibody was used to detect enzyme production and processing during the developmental cycle using a cell culture infection model. Collectively, our data indicate that non-C. trachomatis species (and a single C. trachomatis serovar: E) produce active AaxB. Chlamydia strains used in this study include Chlamydia muridarum strain Nigg, C. trachomatis serovar D strain UW-3/CX, Chlamydia psittaci GSK-3 inhibitor review strain 6BC, Chlamydia caviae strain SP6 (Binet et al., 2010), and C. trachomatis serovar E strain UW-5/CX. Chlamydia pecorum strain E58 DNA was provided by Patrik
Bavoil (University of Maryland). The previously unreported aaxB sequences for C. caviae SP6 and C. trachomatis E strain UW-5/CX were deposited in GenBank under accession numbers JX287368 and JX287367, respectively. Escherichia coli strain MG1655 was used for the acid resistance complementation assays, while E. coli Rosetta-gami2 (DE3; Novagen) was used for AaxB expression and purification. A pBAD/HisA vector (modified during cloning to remove the histidine tag coding region; Invitrogen) carrying aaxB from C. pneumoniae strain Kajaani 6 or adiA from E. coli strain MG1655 was provided by David Graham (Oak Ridge National Laboratory). Primers used to
amplify the different aaxB variants are listed in Supporting information, Table S1. PCR-amplified products were digested and ligated into the NcoI and HindIII sites on the pBAD/HisA vector (without the histidine tag). Constructs were then electroporated into ΔadiA E. coli strain MG1655. The aaxB gene from C. caviae also was PCR-amplified (primers listed in Table S1) for cloning Staurosporine manufacturer into a pET-19b expression vector (Invitrogen). PCR-amplified products were digested and ligated into the NdeI and BamHI sites on pET-19b and then electroporated into E. coli strain Rosetta-gami2 (DE3). All constructs were sequence verified at the Biomedical Instrumentation Center at the Uniformed Services University. The adiA gene was deleted from E. coli strain MG1655 using the lambda red method of linear recombination with the primers listed in Table S1 (Datsenko & Wanner, 2000). After PCR verification of the constructed ΔadiA::kan mutation, the allele was moved into a clean E. coli MG1655 background via P1L4 transduction (Miller, 1972).