Structure-Function Studies of the Co2 Uptake Complex In
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STRUCTURE-FUNCTION STUDIES OF THE CO2 UPTAKE COMPLEX IN CYANOBACTERIA By JULIANA ARTIER Bachelor of Science in Biological Science Universidade Federal de São Carlos São Carlos, SP, Brazil 2007 Master of Science in Genetics and Evolution Universidade Federal de São Carlos São Carlos, SP, Brazil 2010 Submitted to the Faculty of the Graduate College of the Oklahoma State University in partial fulfillment of the requirements for the Degree of DOCTOR OF PHILOSOPHY July, 2018 STRUCTURE-FUNCTION STUDIES OF THE CO2 UPTAKE COMPLEX IN CYANOBACTERIA Dissertation Approved: Robert L. Burnap Dissertation Adviser Rolf A. Prade Marianna A. Patrauchan Wouter D. Hoff William J. Henley ii ACKNOWLEDGEMENTS I want to thank my advisor and mentor Robert Burnap for all the support, in the past, present, and future. I also greatly appreciate the time and efforts my committee members kindly devoted towards my academic development. I am grateful to Dean G. Price for detailed help with the Ci affinity assays and collaboration in this study. Thanks to Anthony D. Kappell and Steven Holland for contribution in the molecular design of the CCM knockout constructs. Also, I am extremely thankful to all involved in this project: Steven Holland for assistance constructing the CCM knockout mutants and with PAM analysis, Minquan Zhang for collaboration on protein expression experiments, Neil T. Miller for help with Western blots, and Prachi Zawar for collaboration in constructing the Arthrospira heterologous expression systems. Also, I appreciate the kind gifts of vectors: the integration vectors provided by H. Wang and Wim Vermaas; MBP containing vectors from Junpeng Deng. I want to thank the assistance of Janet Rogers and Steven Hartson for DNA sequencing and mass spectrometry analyses within the DNA/Protein Resource Facility at Oklahoma State University, supported by the NSF MRI and EPSCoR programs (award #0722494). This dissertation was only possible due to financial support by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, grant no. DE- iii Acknowledgements reflect the views of the author and are not endorsed by committee members or Oklahoma State University. FG02-08ER15968. During all the years of my PhD studies, my family and friends were essential, although not directly involved in the project, but in my daily life, sharing the good and the bad. I am extremely grateful to all the emotional support and loving moments. At the Burnap lab I had the pleasure to share a great, professional and fun environment by the side of Han Bao, Steven Holland, Preston Dilbeck, Aparna Nagarajan, Neil Miller and Anton Avramov, making the daily work so much more enjoyable, and I am so grateful. Also, I am thankful to the friends I made along the way, Abhaya Ranganathan, Amanda Behar, Ruth Weidman, Rachana Rathod, Sharmily Khanam, Prachi Zawar, Shaikh Saad. I am grateful for the family environment and amazing moments shared with the Brazilian community in Stillwater, including Hevila Brognaro, Mariane Zubieta, Zeyna Abramson, with a special thanks to Beatriz Solera and family for opening their hearts and home. I am also grateful to Bruno Sauce, for pushing me towards better worlds. Special thanks to my loving and kind husband Raid Alzaher, who I met at OSU, for all the support, patience and for never letting me give up. I am grateful to my family, my brother Alexandre, aunts, uncles, grandparents, for the emotional support and understanding. I dedicate this dissertation to my parents, Marli and Irineu, who always stand by my side, even when an ocean away. iv Acknowledgements reflect the views of the author and are not endorsed by committee members or Oklahoma State University. Name: JULIANA ARTIER Date of Degree: JULY, 2018 Title of Study: STRUCTURE-FUNCTION STUDIES OF TH CO2 UPTAKE COMPLEX IN CYANOBACTERIA Major Field: MICROBIOLOGY & MOLECULAR BIOLOGY Abstract: Increase of CO2 atmospheric level has led to an intense search for solutions to mitigate the problem. A natural pathway exists in photosynthesis where CO2 is fixed into biomass. Cyanobacteria, which constitute a large phylum of natural oxygenic photosynthetic bacteria, have a huge potential for bioengineering. This includes candidates for use in diverse CO2 capture and storage projects and the potential to redirect its energy for the production of valuable compounds. Our aim in this project is to understand the structure-function of Cup (CO2 uptake) proteins in the NDH-13,4 complex, part of the cyanobacterial CO2 concentrating mechanism (CCM). Cyanobacteria have five CCM systems responsible for increasing inorganic carbon (Ci) concentration inside of the cell, an effort to raise CO2 level close to Rubisco, the main enzyme responsible for carbon fixation. Among them, two CO2 uptake systems are specialized NDH-1 complexes, NDH- 13 (NdhF3/NdhD3/CupA/CupS) and NDH-14 (NdhF4/NdhD4/CupB), which have very little known about their mechanism. CO2 is usually regulated in living organisms by - carbonic anhydrases (CAs), enzymes that catalyzes the interconversion of CO2 and HCO3 . The hypothesis is that Cup, in the NDH-13,4 complex, is involved in this (non)reversible reaction, possibly coupled with release of a proton across the membrane. We constructed a double knockout mutant, where no NDH-13,4 is produced by the bacteria, and introduced the whole cupA operon under Rubisco promoter control in Synechocystis 6803. Physiological analysis of Ci depleted mutants with chlorophyll fluorescence traces and O2 evolution dependent on Ci, show a high Ci requirement feature on the double knockout mutants. However, the strain expressing constitutively NDH-13 lost its high CO2-requiring phenotype, displaying restored cell CO2 uptake. In parallel, we also analyzed Synechococcus 7942 mutants with no functional CO2 uptake systems, later complemented with only chpX (cupB). These systems were used in studies directed to analyze the effect of point mutations replacing amino acids (His/Cys) of CupA/CupB proteins to evaluate their potential role on CO2 uptake in cyanobacteria. v TABLE OF CONTENTS Chapter Page 1 CHAPTER I ........................................................................................................... 1 INTRODUCTION AND LITERATURE REVIEW .................................................... 1 1.1 INTRODUCTION ................................................................................................. 1 1.2 CYANOBACTERIA, PHOTOSYNTHESIS AND CO2 ADAPTATION............................... 5 1.3 PHOTOSYNTHESIS AND THE PHOTOSYNTHETIC ELECTRON TRANSPORT CHAIN ...... 7 1.4 CARBON FIXATION IN CYANOBACTERIA ........................................................... 15 1.5 CO2 CONCENTRATING MECHANISMS IN CYANOBACTERIA .................................. 16 1.5.1 Carboxysome ............................................................................................. 19 1.5.2 Bicarbonate transporters: BCT1, BicA and SbtA ........................................ 21 1.6 NDH-1 COMPLEX AND CUP PROTEINS .............................................................. 23 1.7 CARBONIC ANHYDRASES, STRUCTURE-FUNCTION OVERVIEW AND IMPORTANCE IN CYANOBACTERIA ........................................................................................................ 29 1.8 QUESTIONS AND GOALS ................................................................................... 33 2 CHAPTER II ....................................................................................................... 35 EXPERIMENTAL PROCEDURES ........................................................................... 35 2.1 MATERIALS AND METHODS ............................................................................. 35 2.2 CULTURE AND GROWTH CONDITIONS ............................................................... 35 2.3 STRAINS AND MOLECULAR CONSTRUCTS .......................................................... 37 2.4 CELL SAMPLE PREPARATION ............................................................................ 40 2.5 CI AFFINITY AND OXYGEN EVOLUTION ASSAYS. ................................................ 41 2.6 CHL AND NADPH FLUORESCENCE AND P700 SPECTROSCOPY .......................... 42 2.6.1 Chl and NADPH fluorescence .................................................................... 42 vi 2.6.2 P700 spectroscopy ..................................................................................... 43 2.7 SDS-PAGE AND IMMUNOBLOT ANALYSIS ....................................................... 44 3 CHAPTER III ...................................................................................................... 47 HETEROLOGOUS EXPRESSION OF CUPA ......................................................... 47 3.1 INTRODUCTION ............................................................................................... 47 3.2 MATERIAL AND METHODS .............................................................................. 48 3.2.1 Molecular Construction.............................................................................. 48 3.2.2 Expression of CupA protein in E. coli ......................................................... 49 3.2.3 Protein purification, ................................................................................... 50 3.2.4 Antibody production ................................................................................... 52 3.2.5 CD spectroscopy ........................................................................................ 52 3.2.6 Zn binding evaluation and CA activity .......................................................