Romano Maria, van de Weerd Robert, Brouwer Femke C C, Roviello Giovanni N, Lacroix Ruben, Sparrius Marion, van den Brink-van Stempvoort Gunny, Maaskant Janneke J, van der Sar Astrid M, Appelmelk Ben J, Geurtsen Jeroen J, Berisio Rita
Institute of Biostructures and Bioimaging, National Research Council, Via Mezzocannone 16, I-80134 Naples, Italy.
Department of Medical Microbiology and Infection Control, VU University Medical Center, Van der Boechorststraat 7, Amsterdam, 1081 BT, the Netherlands.
Structure. 2014 May 6;22(5):719-30. doi: 10.1016/j.str.2014.01.014. Epub 2014 Apr 3.
The cell-envelope of Mycobacterium tuberculosis plays a key role in bacterial virulence and antibiotic resistance. Little is known about the molecular mechanisms of regulation of cell-envelope formation. Here, we elucidate functional and structural properties of RNase AS, which modulates M. tuberculosis cell-envelope properties and strongly impacts bacterial virulence in vivo. The structure of RNase AS reveals a resemblance to RNase T from Escherichia coli, an RNase of the DEDD family involved in RNA maturation. We show that RNase AS acts as a 3'-5'-exoribonuclease that specifically hydrolyzes adenylate-containing RNA sequences. Also, crystal structures of complexes with AMP and UMP reveal the structural basis for the observed enzyme specificity. Notably, RNase AS shows a mechanism of substrate recruitment, based on the recognition of the hydrogen bond donor NH2 group of adenine. Our work opens a field for the design of drugs able to reduce bacterial virulence in vivo.
结核分枝杆菌的细胞壁在细菌毒力和抗生素耐药性方面起着关键作用。关于细胞壁形成的分子调控机制，我们知之甚少。在此，我们阐明了核糖核酸酶AS的功能和结构特性，它可调节结核分枝杆菌的细胞壁特性，并在体内对细菌毒力产生强烈影响。核糖核酸酶AS的结构显示出与大肠杆菌核糖核酸酶T相似，后者是一种参与RNA成熟的DEDD家族核糖核酸酶。我们表明，核糖核酸酶AS作为一种3'-5'-外切核糖核酸酶，特异性水解含腺苷酸的RNA序列。此外，与AMP和UMP形成的复合物的晶体结构揭示了所观察到的酶特异性的结构基础。值得注意的是，核糖核酸酶AS基于对腺嘌呤氢键供体NH2基团的识别，展示了一种底物募集机制。我们为设计能够在体内降低细菌毒力的药物开辟了一个领域。
