title: Alteramide B is a microtubule antagonist of inhibiting Candida albicans.
abstract: Alteramide B (ATB), isolated from Lysobacter enzymogenes C3, was a new polycyclic tetramate macrolactam (PTM). ATB exhibited potent inhibitory activity against several yeasts, particularly Candida albicans SC5314, but its antifungal mechanism is unknown.
  
  
  
  The structure of ATB was established by extensive spectroscopic analyses, including high-resolution mass spectrometry, 1D- and 2D-NMR, and CD spectra. Flow cytometry, fluorescence microscope, transmission electron microscope, molecular modeling, overexpression and site-directed mutation studies were employed to delineate the anti-Candida molecular mechanism of ATB.
  
  
  
  ATB induced apoptosis in C. albicans through inducing reactive oxygen species (ROS) production by disrupting microtubules. Molecular dynamics studies revealed the binding patterns of ATB to the β-tubulin subunit. Overexpression of the wild type and site-directed mutants of the β-tubulin gene (TUBB) changed the sensitivity of C. albicans to ATB, confirming the binding of ATB to β-tubulin, and indicating that the binding sites are L215, L217, L273, L274 and R282. In vivo, ATB significantly improved the survival of the candidiasis mice and reduced fungal burden.
  
  
  
  The molecular mechanism underlying the ATB-induced apoptosis in C. albicans is through inhibiting tubulin polymerization that leads to cell cycle arrest at the G2/M phase. The identification of ATB and the study of its activity provide novel mechanistic insights into the mode of action of PTMs against the human pathogen.
  
  
  
  This study shows that ATB is a new microtubule inhibitor and a promising anti-Candida lead compound. The results also support β-tubulin as a potential target for anti-Candida drug discovery.
authors.affiliation: Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, No. 44 West Wenhua Road, Jinan, Shandong 250012, PR China.
authors.forename: Yanjiao
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, No. 44 West Wenhua Road, Jinan, Shandong 250012, PR China.
authors.forename: Yaoyao
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, No. 44 West Wenhua Road, Jinan, Shandong 250012, PR China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Li
authors.affiliation: Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, No. 44 West Wenhua Road, Jinan, Shandong 250012, PR China.
authors.forename: Juanli
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, No. 44 West Wenhua Road, Jinan, Shandong 250012, PR China.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Lu
authors.affiliation: State Key laboratory of Microbial Technology, Shandong University, No. 27 South Shanda Road, Jinan, Shandong 250100, PR China.
authors.forename: Haoxin
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, No. 44 West Wenhua Road, Jinan, Shandong 250012, PR China; State Key laboratory of Microbial Technology, Shandong University, No. 27 South Shanda Road, Jinan, Shandong 250100, PR China. Electronic address: yshen@sdu.edu.cn.
authors.forename: Yuemao
authors.initials: Y
authors.lastname: Shen
authors.affiliation: State Key laboratory of Microbial Technology, Shandong University, No. 27 South Shanda Road, Jinan, Shandong 250100, PR China; Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA. Electronic address: ldu3@unl.edu.
authors.forename: Liangcheng
authors.initials: L
authors.lastname: Du
mesh_terms: D000818:Animals; D000935:Antifungal Agents / Q000378:metabolism / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001665:Binding Sites / Q000187:drug effects; D002176:Candida albicans / Q000187:drug effects* / Q000472:pathogenicity; D002177:Candidiasis / Q000188:drug therapy* / Q000382:microbiology; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D007854:Lead / Q000494:pharmacology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008870:Microtubules / Q000187:drug effects*; D056004:Molecular Dynamics Simulation; D017382:Reactive Oxygen Species / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism*; D050257:Tubulin Modulators / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000935:Antifungal Agents; D047029:Lactams, Macrocyclic; D017382:Reactive Oxygen Species; D014404:Tubulin; D050257:Tubulin Modulators; C000620184:alteramide B; D007854:Lead
keywords: Alteramide B; Apoptosis; Candida albicans SC5314; Reactive oxygen species; β-Tubulin