Researcher:
Ertem, Fatma Betül

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PhD Student

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Fatma Betül

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Ertem

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Ertem, Fatma Betül

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2021 - 20225

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Researcher Of Publications: search.filters.isAuthorOfPublication.2e42ae13-f540-4015-a7c9-acbb31520bf4

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Now showing 1 - 5 of 5
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    PublicationOpen Access
    Protocol for structure determination of SARS-CoV-2 main protease at near-physiological-temperature by serial femtosecond crystallography
    (Cell Press, 2022) Dao, E. Han; Su, Zhen; Poitevin, Frederic; Yoon, Chun Hong; Kupitz, Christopher; Hayes, Brandon; Liang, Mengning; Hunter, Mark S.; Batyuk, Alexander; Sierra, Raymond G.; Ketawala, Gihan; Botha, Sabine; Department of Molecular Biology and Genetics; Ertem, Fatma Betül; Güven, Ömür; Büyükdağ, Cengizhan; Göcenler, Oktay; Ayan, Esra; Yüksel, Büşra; Gül, Mehmet; Karakadıoğlu, Gözde Usta; Çakılkaya, Barış; Johnson, Jerome Austin; Demirci, Hasan; Dağ, Çağdaş; Undergraduate Student; PhD Student; Master Student; Faculty Member; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Koç Üniversitesi İş Bankası Enfeksiyon Hastalıkları Uygulama ve Araştırma Merkezi (EHAM) / Koç University İşbank Center for Infectious Diseases (KU-IS CID); Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 307350
    The SARS-CoV-2 main protease of (Mpro) is an important target for SARS-CoV-2 related drug repurposing and development studies. Here, we describe the steps for structural characterization of SARS-CoV-2 Mpro, starting from plasmid preparation and protein purification. We detail the steps for crystallization using the sitting drop, microbatch (under oil) approach. Finally, we cover data collection and structure determination using serial femtosecond crystallography.
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    PublicationOpen Access
    Structural insight into host plasma membrane association and assembly of HIV-1 matrix protein
    (Nature Publishing Group (NPG), 2021) Çiftçi, Halilibrahim; Tateishi, Hiroshi; Koiwai, Kotaro; Koga, Ryoko; Anraku, Kensaku; Monde, Kazuaki; Destan, Ebru; Yüksel, Büşra; Ayan, Esra; Yıldırım, Günseli; Yığın, Merve; Sierra, Raymond G.; Yoon, Chun Hong; Su, Zhen; Liang, Mengling; Acar, Burçin; Haliloğlu, Türkan; Otsuka, Masami; Yumoto, Fumiaki; Fujita, Mikako; Senda, Toshiya; Department of Molecular Biology and Genetics; Demirci, Hasan; Dağ, Çağdaş; Güven, Ömür; Ertem, Fatma Betül; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Koç Üniversitesi İş Bankası Enfeksiyon Hastalıkları Uygulama ve Araştırma Merkezi (EHAM) / Koç University İşbank Center for Infectious Diseases (KU-IS CID); College of Sciences; Graduate School of Sciences and Engineering; 307350; N/A; N/A; N/A; N/A; N/A
    Oligomerization of Pr55(Gag) is a critical step of the late stage of the HIV life cycle. It has been known that the binding of IP6, an abundant endogenous cyclitol molecule at the MA domain, has been linked to the oligomerization of Pr55(Gag). However, the exact binding site of IP6 on MA remains unknown and the structural details of this interaction are missing. Here, we present three high-resolution crystal structures of the MA domain in complex with IP6 molecules to reveal its binding mode. Additionally, extensive Differential Scanning Fluorimetry analysis combined with cryo- and ambient-temperature X-ray crystallography and GNM-based transfer entropy calculations identify the key residues that participate in IP6 binding. Our data provide novel insights about the multilayered HIV-1 virion assembly process that involves the interplay of IP6 with PIP2, a phosphoinositide essential for the binding of Pr55(Gag) to membrane. IP6 and PIP2 have neighboring alternate binding sites within the same highly basic region (residues 18-33). This indicates that IP6 and PIP2 bindings are not mutually exclusive and may play a key role in coordinating virion particles' membrane localization. Based on our three different IP6-MA complex crystal structures, we propose a new model that involves IP6 coordination of the oligomerization of outer MA and inner CA domain's 2D layers during assembly and budding.
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    PublicationOpen Access
    Case study of high-throughput drug screening and remote data collection for SARS-CoV-2 main protease by using serial femtosecond X-ray crystallography
    (Multidisciplinary Digital Publishing Institute (MDPI), 2021) Botha, Sabine; Ketawala, Gihan; Su, Zhen; Hayes, Brandon; Poitevin, Frederic; Batyuk, Alexander; Yoon, Chun Hong; Kupitz, Christopher; Durdağı, Serdar; Sierra, Raymond G.; Department of Molecular Biology and Genetics; Department of Chemical and Biological Engineering; Güven, Ömür; Gül, Mehmet; Ayan, Esra; Johnson, Jerome Austin; Çakılkaya, Barış; Karakadıoğlu, Gözde Usta; Ertem, Fatma Betül; Tokay, Nurettin; Yüksel, Büşra; Göcenler, Oktay; Büyükdağ, Cengizhan; Demirci, Hasan; PhD Student; Master Student; Undergraduate Student; Undergraduate Student; Faculty Member; Department of Molecular Biology and Genetics; Department of Chemical and Biological Engineering; Koç Üniversitesi İş Bankası Enfeksiyon Hastalıkları Uygulama ve Araştırma Merkezi (EHAM) / Koç University İşbank Center for Infectious Diseases (KU-IS CID); Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 307350
    Since early 2020, COVID-19 has grown to affect the lives of billions globally. A worldwide investigation has been ongoing for characterizing the virus and also for finding an effective drug and developing vaccines. As time has been of the essence, a crucial part of this research has been drug repurposing; therefore, confirmation of in silico drug screening studies have been carried out for this purpose. Here we demonstrated the possibility of screening a variety of drugs efficiently by leveraging a high data collection rate of 120 images/second with the new low-noise, high dynamic range ePix10k2M Pixel Array Detector installed at the Macromolecular Femtosecond Crystallography (MFX) instrument at the Linac Coherent Light Source (LCLS). The X-ray Free-Electron Laser (XFEL) is used for remote high-throughput data collection for drug repurposing of the main protease (Mpro) of SARS-CoV-2 at ambient temperature with mitigated X-ray radiation damage. We obtained multiple structures soaked with nine drug candidate molecules in two crystal forms. Although our drug binding attempts failed, we successfully established a high-throughput Serial Femtosecond X-ray crystallographic (SFX) data collection protocol.
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    PublicationOpen Access
    Cooperative allostery and structural dynamics of streptavidin at cryogenic- and ambient-temperature
    (Springer Nature, 2022) Yefanov, Oleksandr M.; Barty, Anton; Tolstikova, Alexandra; Ketawala, Gihan K.; Botha, Sabine; Dao, E. Han; Hayes, Brandon; Liang, Mengning; Seaberg, Matthew H.; Hunter, Mark S.; Batyuk, Alexander; Mariani, Valerio; Su, Zhen; Poitevin, Frederic; Yoon, Chun Hong; Kupitz, Christopher; Cohen, Aina; Doukov, Tzanko; Sierra, Raymond G.; Department of Molecular Biology and Genetics; Dağ, Çağdaş; Ayan, Esra; Yüksel, Büşra; Destan, Ebru; Ertem, Fatma Betül; Yıldırım, Günseli; Eren, Meryem; Demirci, Hasan; Faculty Member; PhD Student; Faculty Member; Department of Molecular Biology and Genetics; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 307350
    Ayan et al. report two structures of the protein streptavidin - one at ambient temperature determined using serial femtosecond crystallography and a second one determined at cryogenic temperature. These results provide insights into the structural dynamics of apo streptavidin and reveal a cooperative allostery between monomers for binding to biotin, and the findings are supported by GNM analysis. Multimeric protein assemblies are abundant in nature. Streptavidin is an attractive protein that provides a paradigm system to investigate the intra- and intermolecular interactions of multimeric protein complexes. Also, it offers a versatile tool for biotechnological applications. Here, we present two apo-streptavidin structures, the first one is an ambient temperature Serial Femtosecond X-ray crystal (Apo-SFX) structure at 1.7 angstrom resolution and the second one is a cryogenic crystal structure (Apo-Cryo) at 1.1 angstrom resolution. These structures are mostly in agreement with previous structural data. Combined with computational analysis, these structures provide invaluable information about structural dynamics of apo streptavidin. Collectively, these data further reveal a novel cooperative allostery of streptavidin which binds to substrate via water molecules that provide a polar interaction network and mimics the substrate biotin which displays one of the strongest affinities found in nature.
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    PublicationOpen Access
    Near-physiological-temperature serial crystallography reveals conformations of SARS-CoV-2 main protease active site for improved drug repurposing
    (Elsevier, 2021) Durdağı, Serdar; Doğan, Berna; Avşar, Timuçin; Erol, İsmail; Çalış, Şeyma; Orhan, Müge D.; Aksoydan, Busecan; Şahin, Kader; Oktay, Lalehan; Tolu, İlayda; Olkan, Alpsu; Erdemoğlu, Ece; Yefanov, Oleksandr M.; Dao, E. Han; Hayes, Brandon; Liang, Mengning; Seaberg, Matthew H.; Hunter, Mark S.; Batyuk, Alex; Mariani, Valerio; Su, Zhen; Poitevin, Frederic; Yoon, Chun Hong; Kupitz, Christopher; Sierra, Raymond G.; Snell, Edward H.; Department of Molecular Biology and Genetics; Department of Chemical and Biological Engineering; N/A; Demirci, Hasan; Dağ, Çağdaş; Büyükdağ, Cengizhan; Ertem, Fatma Betül; Yıldırım, Günseli; Destan, Ebru; Güven, Ömür; Ayan, Esra; Yüksel, Büşra; Göcenler, Oktay; Can, Özgür; Özabrahamyan, Serena; Tanısalı, Gökhan; Faculty Member; Faculty Member; Undergraduate Student; PhD Student; Department of Molecular Biology and Genetics; Department of Chemical and Biological Engineering; Koç Üniversitesi İş Bankası Enfeksiyon Hastalıkları Uygulama ve Araştırma Merkezi (EHAM) / Koç University İşbank Center for Infectious Diseases (KU-IS CID); College of Sciences; Graduate School of Sciences and Engineering; School of Nursing; 307350; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A
    The COVID-19 pandemic has resulted in 198 million reported infections and more than 4 million deaths as of July 2021 (covid19.who.int). Research to identify effective therapies for COVID-19 includes: (1) designing a vaccine as future protection; (2) de novo drug discovery; and (3) identifying existing drugs to repurpose them as effective and immediate treatments. To assist in drug repurposing and design, we determine two apo structures of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease at ambient temperature by serial femtosecond X-ray crystallography. We employ detailed molecular simulations of selected known main protease inhibitors with the structures and compare binding modes and energies. The combined structural and molecular modeling studies not only reveal the dynamics of small molecules targeting the main protease but also provide invaluable opportunities for drug repurposing and structure-based drug design strategies against SARS-CoV-2.