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Sumyk M, Himpich S, Foong WE, Herrmann A, Pos KM, Tam HK. Binding of Tetracyclines to Acinetobacter baumannii TetR Involves Two Arginines as Specificity Determinants. Front Microbiol 2021; 12:711158. [PMID: 34349752 PMCID: PMC8326586 DOI: 10.3389/fmicb.2021.711158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 06/23/2021] [Indexed: 11/13/2022] Open
Abstract
Acinetobacter baumannii is an important nosocomial pathogen that requires thoughtful consideration in the antibiotic prescription strategy due to its multidrug resistant phenotype. Tetracycline antibiotics have recently been re-administered as part of the combination antimicrobial regimens to treat infections caused by A. baumannii. We show that the TetA(G) efflux pump of A. baumannii AYE confers resistance to a variety of tetracyclines including the clinically important antibiotics doxycycline and minocycline, but not to tigecycline. Expression of tetA(G) gene is regulated by the TetR repressor of A. baumannii AYE (AbTetR). Thermal shift binding experiments revealed that AbTetR preferentially binds tetracyclines which carry a O-5H moiety in ring B, whereas tetracyclines with a 7-dimethylamino moiety in ring D are less well-recognized by AbTetR. Confoundingly, tigecycline binds to AbTetR even though it is not transported by TetA(G) efflux pump. Structural analysis of the minocycline-bound AbTetR-Gln116Ala variant suggested that the non-conserved Arg135 interacts with the ring D of minocycline by cation-π interaction, while the invariant Arg104 engages in H-bonding with the O-11H of minocycline. Interestingly, the Arg135Ala variant exhibited a binding preference for tetracyclines with an unmodified ring D. In contrast, the Arg104Ala variant preferred to bind tetracyclines which carry a O-6H moiety in ring C except for tigecycline. We propose that Arg104 and Arg135, which are embedded at the entrance of the AbTetR binding pocket, play important roles in the recognition of tetracyclines, and act as a barrier to prevent the release of tetracycline from its binding pocket upon AbTetR activation. The binding data and crystal structures obtained in this study might provide further insight for the development of new tetracycline antibiotics to evade the specific efflux resistance mechanism deployed by A. baumannii.
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Affiliation(s)
- Manuela Sumyk
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Stephanie Himpich
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Wuen Ee Foong
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Andrea Herrmann
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Klaas M Pos
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Heng-Keat Tam
- Institute of Biochemistry, Goethe-University Frankfurt, Frankfurt, Germany
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Coutandin D, Osterburg C, Srivastav RK, Sumyk M, Kehrloesser S, Gebel J, Tuppi M, Hannewald J, Schäfer B, Salah E, Mathea S, Müller-Kuller U, Doutch J, Grez M, Knapp S, Dötsch V. Quality control in oocytes by p63 is based on a spring-loaded activation mechanism on the molecular and cellular level. eLife 2016; 5. [PMID: 27021569 PMCID: PMC4876613 DOI: 10.7554/elife.13909] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/28/2016] [Indexed: 01/07/2023] Open
Abstract
Mammalian oocytes are arrested in the dictyate stage of meiotic prophase I for long
periods of time, during which the high concentration of the p53 family member TAp63α
sensitizes them to DNA damage-induced apoptosis. TAp63α is kept in an inactive and
exclusively dimeric state but undergoes rapid phosphorylation-induced tetramerization
and concomitant activation upon detection of DNA damage. Here we show that the TAp63α
dimer is a kinetically trapped state. Activation follows a spring-loaded mechanism
not requiring further translation of other cellular factors in oocytes and is
associated with unfolding of the inhibitory structure that blocks the tetramerization
interface. Using a combination of biophysical methods as well as cell and ovary
culture experiments we explain how TAp63α is kept inactive in the absence of DNA
damage but causes rapid oocyte elimination in response to a few DNA double strand
breaks thereby acting as the key quality control factor in maternal reproduction. DOI:http://dx.doi.org/10.7554/eLife.13909.001 The irradiation and chemotherapy drugs that are used to destroy cancer cells also
damage healthy cells. Germ cells – from which egg cells and sperm cells develop – are
particularly vulnerable as they contain sensitive quality control mechanisms that
kill any cell that contain damaged DNA. Consequently, after surviving cancer many
patients are confronted with infertility. A protein called p63, which is closely related to another protein that suppresses the
formation of tumors, plays an essential role in detecting and responding to DNA
damage. In immature egg cells (also known as oocytes), p63 mostly exists in an
inactive form. The protein then switches to an active form when DNA damage is
detected to trigger the process of cell self-destruction. Now, Coutandin, Osterburg et al. have performed a range of biochemical, biophysical
and cell culture experiments to study how p63 is kept in its inactive form in the
oocytes of mice. The experiments showed that in the inactive form, the two ends of
the protein form a sheet that closes a key site on the protein and prevents it from
changing into its active form. However, this closed form can be thought of as being
like a spring-loaded trap – it doesn’t take much energy to spring the trap and open
the protein into its active form. Once this change has occurred, it is
irreversible. Coutandin, Osterburg et al. also found that the oocytes of mice already contain all
the proteins necessary to activate p63. This means that once the switch to the active
form is triggered there is no delay waiting for other proteins to be made, which
makes oocytes extremely sensitive to DNA damage. Further work is now needed to
investigate the exact molecular mechanisms behind the activation of p63. DOI:http://dx.doi.org/10.7554/eLife.13909.002
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Affiliation(s)
- Daniel Coutandin
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.,Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt, Germany.,Cluster of Excellence Macromolecular Complexes, Goethe University, Frankfurt, Germany
| | - Christian Osterburg
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.,Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt, Germany.,Cluster of Excellence Macromolecular Complexes, Goethe University, Frankfurt, Germany
| | - Ratnesh Kumar Srivastav
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.,Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt, Germany.,Cluster of Excellence Macromolecular Complexes, Goethe University, Frankfurt, Germany
| | - Manuela Sumyk
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.,Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt, Germany.,Cluster of Excellence Macromolecular Complexes, Goethe University, Frankfurt, Germany
| | - Sebastian Kehrloesser
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.,Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt, Germany.,Cluster of Excellence Macromolecular Complexes, Goethe University, Frankfurt, Germany
| | - Jakob Gebel
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.,Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt, Germany.,Cluster of Excellence Macromolecular Complexes, Goethe University, Frankfurt, Germany
| | - Marcel Tuppi
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.,Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt, Germany.,Cluster of Excellence Macromolecular Complexes, Goethe University, Frankfurt, Germany
| | - Jens Hannewald
- MS-DTB-C Protein Purification, Merck KGaA, Darmstadt, Germany
| | - Birgit Schäfer
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.,Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt, Germany.,Cluster of Excellence Macromolecular Complexes, Goethe University, Frankfurt, Germany
| | - Eidarus Salah
- Nuffield Department of Medicine, Structural Genomics Consortium, University of Oxford, Oxford, United Kingdom
| | - Sebastian Mathea
- Nuffield Department of Medicine, Structural Genomics Consortium, University of Oxford, Oxford, United Kingdom
| | | | - James Doutch
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot, United Kingdom
| | | | - Stefan Knapp
- Nuffield Department of Medicine, Structural Genomics Consortium, University of Oxford, Oxford, United Kingdom.,Institute for Pharmaceutical Chemistry, Goethe University, Frankfurt, Germany.,Buchmann Institute for Molecular Life Science, Goethe University, Frankfurt, Germany
| | - Volker Dötsch
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.,Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt, Germany.,Cluster of Excellence Macromolecular Complexes, Goethe University, Frankfurt, Germany
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