Functional Characterization of Corynebacterium glutamicum Mycothiol S-Conjugate Amidase
PLOS ONE
Authors: Si, Meiru; Long, Mingxiu; Chaudhry, Muhammad Tausif; Xu, Yixiang; Zhang, Pan; Zhang, Lei; Shen, Xihui
Abstract
The present study focuses on the genetic and biochemical characterization of mycothiol S-conjugate amidase (Mca) of Corynebacterium glutamicum. Recombinant C. glutamicum Mca was heterologously expressed in Escherichia coli and purified to apparent homogeneity. The molecular weight of native Mca protein determined by gel filtration chromatography was 35 kDa, indicating that Mca exists as monomers in the purification condition. Mca showed amidase activity with mycothiol S-conjugate of monobromobimane (MSmB) in vivo while mca mutant lost the ability to cleave MSmB. In addition, Mca showed limited deacetylase activity with N-acetyl-D-glucosamine (GlcNAc) as substrate. Optimum pH for amidase activity was between 7.5 and 8.5, while the highest activity in the presence of Zn2+ confirmed Mca as a zinc metalloprotein. Amino acid residues conserved among Mca family members were located in C. glutamicum Mca and site-directed mutagenesis of these residues indicated that Asp14, Tyr137, His139 and Asp141 were important for activity. The mca deletion mutant showed decreased resistance to antibiotics, alkylating agents, oxidants and heavy metals, and these sensitive phenotypes were recovered in the complementary strain to a great extent. The physiological roles of Mca in resistance to various toxins were further supported by the induced expression of Mca in C. glutamicum under various stress conditions, directly under the control of the stress-responsive extracytoplasmic function-sigma (ECF-s) factor SigH.
The role of Pax2 in mouse prostate development
PROSTATE
Authors: Xu, Ben; Hariharan, Arun; Rakshit, Sabita; Dressler, Gregory R.; Wellik, Deneen M.
Abstract
BACKGROUND Loss-of-function of Pax2 results in severe defects of the male reproductive system, and Pax2 expression is detected in mouse prostate lobes and human prostatic cancers. However, the role for Pax2 in prostate development remains poorly understood. METHODS. The expression of Pax2 was examined by in situ hybridization at various developmental stages. Urogenital sinuses were dissected out at E18.5 from mouse Pax2 mutants and controls, cultured in vitro or grafted under the renal capsule of CD1 nude mice. The expression of prostate developmental regulatory factors was analyzed by semi- quantitative real- time PCR or immuohistochemistry. RESULTS. Pax2 is expressed in the epithelial cells of prostate buds. Loss- of- function of Pax2 does not affect the initiation of prostatic buds, but in vitro culture assays show that the prostates of Pax2 mutants are hypomorphic and branching is severely disrupted compared to controls. RT- PCR data from Pax2 mutant prostates demonstrate increased expression levels of dorsolateral prostate marker MSMB and ventral prostate marker SBP and dramatically reduced expression levels of anterior prostate marker TGM4. CONCLUSIONS. Pax2 is essential for mouse prostate development and regulates prostatic ductal growth, branching, and lobe- specific identity. These findings are important for understanding the molecular regulatory mechanisms in prostate development. Prostate 72: 217- 224, 2012. # 2011 Wiley Periodicals, Inc.