1
|
Fernández-Millán P, Vázquez-Monteagudo S, Boix E, Prats-Ejarque G. Exploring the RNase A scaffold to combine catalytic and antimicrobial activities. Structural characterization of RNase 3/1 chimeras. Front Mol Biosci 2022; 9:964717. [PMID: 36188223 PMCID: PMC9515509 DOI: 10.3389/fmolb.2022.964717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 07/27/2022] [Indexed: 11/13/2022] Open
Abstract
Design of novel antibiotics to fight antimicrobial resistance is one of the first global health priorities. Novel protein-based strategies come out as alternative therapies. Based on the structure-function knowledge of the RNase A superfamily we have engineered a chimera that combines RNase 1 highest catalytic activity with RNase 3 unique antipathogen properties. A first construct (RNase 3/1-v1) was successfully designed with a catalytic activity 40-fold higher than RNase 3, but alas in detriment of its anti-pathogenic activity. Next, two new versions of the original chimeric protein were created showing improvement in the antimicrobial activity. Both second generation versions (RNases 3/1-v2 and -v3) incorporated a loop characteristic of RNase 3 (L7), associated to antimicrobial activity. Last, removal of an RNase 1 flexible loop (L1) in the third version enhanced its antimicrobial properties and catalytic efficiency. Here we solved the 3D structures of the three chimeras at atomic resolution by X-ray crystallography. Structural analysis outlined the key functional regions. Prediction by molecular docking of the protein chimera in complex with dinucleotides highlighted the contribution of the C-terminal region to shape the substrate binding cavity and determine the base selectivity and catalytic efficiency. Nonetheless, the structures that incorporated the key features related to RNase 3 antimicrobial activity retained the overall RNase 1 active site conformation together with the essential structural elements for binding to the human ribonuclease inhibitor (RNHI), ensuring non-cytotoxicity. Results will guide us in the design of the best RNase pharmacophore for anti-infective therapies.
Collapse
Affiliation(s)
| | | | - Ester Boix
- *Correspondence: Ester Boix, ; Guillem Prats-Ejarque,
| | | |
Collapse
|
2
|
Frank M, Beccati D, Leeflang BR, Vliegenthart JFG. C-Mannosylation Enhances the Structural Stability of Human RNase 2. iScience 2020; 23:101371. [PMID: 32739833 PMCID: PMC7399192 DOI: 10.1016/j.isci.2020.101371] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 06/22/2020] [Accepted: 07/13/2020] [Indexed: 12/25/2022] Open
Abstract
C-Mannosylation is a relatively rare form of protein glycosylation involving the attachment of an α-mannopyranosyl residue to C-2 of the indole moiety of the amino acid tryptophan. This type of linkage was initially discovered in RNase 2 from human urine but later confirmed to be present in many other important proteins. Based on NMR experiments and extensive molecular dynamics simulations on the hundred microsecond timescale we demonstrate that, for isolated glycopeptides and denatured RNase 2, the C-linked mannopyranosyl residue exists as an ensemble of conformations, among which 1C4 is the most abundant. However, for native RNase 2, molecular dynamics and NMR studies revealed that the mannopyranosyl residue favors a specific conformation, which optimally stabilizes the protein fold through a network of hydrogen bonds and which leads to a significant reduction of the protein dynamics on the microsecond timescale. Our findings contribute to the understanding of the biological role of C-mannosylation. NMR and MD show that C-linked mannose exists as an ensemble of conformations Conformation of mannose is influenced by the protein environment and solvent In RNase 2 mannose favors a conformation that optimally stabilizes the protein fold Efficient methods for analysis of a large number of MD trajectories are presented
Collapse
Affiliation(s)
| | - Daniela Beccati
- Bijvoet Center, Division of Bio-Organic Chemistry, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands
| | - Bas R Leeflang
- Bijvoet Center, Division of Bio-Organic Chemistry, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands
| | - Johannes F G Vliegenthart
- Bijvoet Center, Division of Bio-Organic Chemistry, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands.
| |
Collapse
|
3
|
Grozdanovic MM, Doyle CB, Liu L, Maybruck BT, Kwatia MA, Thiyagarajan N, Acharya KR, Ackerman SJ. Charcot-Leyden crystal protein/galectin-10 interacts with cationic ribonucleases and is required for eosinophil granulogenesis. J Allergy Clin Immunol 2020; 146:377-389.e10. [PMID: 31982451 DOI: 10.1016/j.jaci.2020.01.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 10/28/2019] [Accepted: 01/03/2020] [Indexed: 01/10/2023]
Abstract
BACKGROUND The human eosinophil Charcot-Leyden crystal (CLC) protein is a member of the Galectin superfamily and is also known as galectin-10 (Gal-10). CLC/Gal-10 forms the distinctive hexagonal bipyramidal crystals that are considered hallmarks of eosinophil participation in allergic responses and related inflammatory reactions; however, the glycan-containing ligands of CLC/Gal-10, its cellular function(s), and its role(s) in allergic diseases are unknown. OBJECTIVE We sought to determine the binding partners of CLC/Gal-10 and elucidate its role in eosinophil biology. METHODS Intracellular binding partners were determined by ligand blotting with CLC/Gal-10, followed by coimmunoprecipitation and coaffinity purifications. The role of CLC/Gal-10 in eosinophil function was determined by using enzyme activity assays, confocal microscopy, and short hairpin RNA knockout of CLC/Gal-10 expression in human CD34+ cord blood hematopoietic progenitors differentiated to eosinophils. RESULTS CLC/Gal-10 interacts with both human eosinophil granule cationic ribonucleases (RNases), namely, eosinophil-derived neurotoxin (RNS2) and eosinophil cationic protein (RNS3), and with murine eosinophil-associated RNases. The interaction is independent of glycosylation and is not inhibitory toward endoRNase activity. Activation of eosinophils with INF-γ induces the rapid colocalization of CLC/Gal-10 with eosinophil-derived neurotoxin/RNS2 and CD63. Short hairpin RNA knockdown of CLC/Gal-10 in human cord blood-derived CD34+ progenitor cells impairs eosinophil granulogenesis. CONCLUSIONS CLC/Gal-10 functions as a carrier for the sequestration and vesicular transport of the potent eosinophil granule cationic RNases during both differentiation and degranulation, enabling their intracellular packaging and extracellular functions in allergic inflammation.
Collapse
Affiliation(s)
- Milica M Grozdanovic
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Ill
| | - Christine B Doyle
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Ill
| | - Li Liu
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Ill
| | - Brian T Maybruck
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Ill
| | - Mark A Kwatia
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Ill
| | - Nethaji Thiyagarajan
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - K Ravi Acharya
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Steven J Ackerman
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Ill.
| |
Collapse
|
4
|
Gotte G, Menegazzi M. Biological Activities of Secretory RNases: Focus on Their Oligomerization to Design Antitumor Drugs. Front Immunol 2019; 10:2626. [PMID: 31849926 PMCID: PMC6901985 DOI: 10.3389/fimmu.2019.02626] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/22/2019] [Indexed: 12/11/2022] Open
Abstract
Ribonucleases (RNases) are a large number of enzymes gathered into different bacterial or eukaryotic superfamilies. Bovine pancreatic RNase A, bovine seminal BS-RNase, human pancreatic RNase 1, angiogenin (RNase 5), and amphibian onconase belong to the pancreatic type superfamily, while binase and barnase are in the bacterial RNase N1/T1 family. In physiological conditions, most RNases secreted in the extracellular space counteract the undesired effects of extracellular RNAs and become protective against infections. Instead, if they enter the cell, RNases can digest intracellular RNAs, becoming cytotoxic and having advantageous effects against malignant cells. Their biological activities have been investigated either in vitro, toward a number of different cancer cell lines, or in some cases in vivo to test their potential therapeutic use. However, immunogenicity or other undesired effects have sometimes been associated with their action. Nevertheless, the use of RNases in therapy remains an appealing strategy against some still incurable tumors, such as mesothelioma, melanoma, or pancreatic cancer. The RNase inhibitor (RI) present inside almost all cells is the most efficacious sentry to counteract the ribonucleolytic action against intracellular RNAs because it forms a tight, irreversible and enzymatically inactive complex with many monomeric RNases. Therefore, dimerization or multimerization could represent a useful strategy for RNases to exert a remarkable cytotoxic activity by evading the interaction with RI by steric hindrance. Indeed, the majority of the mentioned RNases can hetero-dimerize with antibody derivatives, or even homo-dimerize or multimerize, spontaneously or artificially. This can occur through weak interactions or upon introducing covalent bonds. Immuno-RNases, in particular, are fusion proteins representing promising drugs by combining high target specificity with easy delivery in tumors. The results concerning the biological features of many RNases reported in the literature are described and discussed in this review. Furthermore, the activities displayed by some RNases forming oligomeric complexes, the mechanisms driving toward these supramolecular structures, and the biological rebounds connected are analyzed. These aspects are offered with the perspective to suggest possible efficacious therapeutic applications for RNases oligomeric derivatives that could contemporarily lack, or strongly reduce, immunogenicity and other undesired side-effects.
Collapse
Affiliation(s)
- Giovanni Gotte
- Biological Chemistry Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Marta Menegazzi
- Biological Chemistry Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| |
Collapse
|
5
|
Rademacher F, Simanski M, Harder J. RNase 7 in Cutaneous Defense. Int J Mol Sci 2016; 17:560. [PMID: 27089327 PMCID: PMC4849016 DOI: 10.3390/ijms17040560] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 04/07/2016] [Accepted: 04/08/2016] [Indexed: 02/07/2023] Open
Abstract
RNase 7 belongs to the RNase A superfamily and exhibits a broad spectrum of antimicrobial activity against various microorganisms. RNase 7 is expressed in human skin, and expression in keratinocytes can be induced by cytokines and microbes. These properties suggest that RNase 7 participates in innate cutaneous defense. In this review, we provide an overview about the role of RNase 7 in cutaneous defense with focus on the molecular mechanism of the antimicrobial activity of RNase 7, the regulation of RNase 7 expression, and the role of RNase 7 in skin diseases.
Collapse
Affiliation(s)
| | - Maren Simanski
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany.
| | - Jürgen Harder
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany.
| |
Collapse
|
6
|
Thiyagarajan N, Acharya KR. Crystal structure of human angiogenin with an engineered loop exhibits conformational flexibility at the functional regions of the molecule. FEBS Open Bio 2012; 3:65-70. [PMID: 23772376 PMCID: PMC3668512 DOI: 10.1016/j.fob.2012.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 12/19/2012] [Accepted: 12/19/2012] [Indexed: 11/18/2022] Open
Abstract
Human angiogenin (ANG) is an angiogenic molecule and a ribonucleolytic enzyme with significant amino acid sequence identity to pancreatic RNase A, plays a critical role in the establishment and growth of tumours. An association between ANG and cancer has been observed in more than 25 clinical studies to date. In addition, ANG has now been shown to be implicated in Amyotrophic Lateral Sclerosis (ALS) and Parkinson's Disease (PD). Structural and biochemical studies so far have showed several distinguishing features of ANG molecule compared to RNase A and provided details of the putative cell binding site, active site, nuclear translocation sequence and the roles of residues in binding and cleaving RNA. A key finding elucidated from the structural study on ANG is the presence of a 'blocked' C-terminus (part of the active site apparatus) compared with RNase A. Here we report the crystal structure of ANG with an 'engineered-loop' from eosinophil derived neurotoxin (a homologue of ANG) which has resulted with local perturbations (conformational flexibility) at the cell binding site and at the C-terminus of the molecule. This experimental observation will now provide a new avenue to design compounds (potent inhibitors) through a structure guided drug design route.
Collapse
Affiliation(s)
| | - K. Ravi Acharya
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| |
Collapse
|
7
|
Hindle KL, Bella J, Lovell SC. Quantitative analysis and prediction of curvature in leucine-rich repeat proteins. Proteins 2009; 77:342-58. [PMID: 19452560 DOI: 10.1002/prot.22440] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Leucine-rich repeat (LRR) proteins form a large and diverse family. They have a wide range of functions most of which involve the formation of protein-protein interactions. All known LRR structures form curved solenoids, although there is large variation in their curvature. It is this curvature that determines the shape and dimensions of the inner space available for ligand binding. Unfortunately, large-scale parameters such as the overall curvature of a protein domain are extremely difficult to predict. Here, we present a quantitative analysis of determinants of curvature of this family. Individual repeats typically range in length between 20 and 30 residues and have a variety of secondary structures on their convex side. The observed curvature of the LRR domains correlates poorly with the lengths of their individual repeats. We have, therefore, developed a scoring function based on the secondary structure of the convex side of the protein that allows prediction of the overall curvature with a high degree of accuracy. We also demonstrate the effectiveness of this method in selecting a suitable template for comparative modeling. We have developed an automated, quantitative protocol that can be used to predict accurately the curvature of leucine-rich repeat proteins of unknown structure from sequence alone. This protocol is available as an online resource at http://www.bioinf.manchester.ac.uk/curlrr/.
Collapse
Affiliation(s)
- K Lauren Hindle
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | | | | |
Collapse
|
8
|
Degradation by stratum corneum proteases prevents endogenous RNase inhibitor from blocking antimicrobial activities of RNase 5 and RNase 7. J Invest Dermatol 2009; 129:2193-201. [PMID: 19262607 DOI: 10.1038/jid.2009.35] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The antimicrobial defense of the skin is partially mediated by RNase 7, an abundant ribonuclease of the stratum corneum (SC). Here, we investigated the expression and regulation of members of the RNase A family and of the endogenous RNase inhibitor (RI) protein in epidermal keratinocytes (KCs). Reverse transcription-PCR screening revealed that KCs expressed not only RNase 7 but also RNase 5, which was shown earlier to kill the yeast Candida albicans, as well as RNase 1, RNase 4, and RI. The mRNA and protein levels of RNase 5, RNase 7, and RI increased during KC differentiation. When RNase 5 and RNase 7 were incubated with RI in vitro, not only their ribonucleolytic activities but also their antimicrobial activities were strongly suppressed. Immunochemical analyses revealed that SC contains RNase 5, whereas RI was not detectable. Unlike recombinant RNase 5, recombinant RI was degraded when exposed to SC extract. The addition of aprotinin prevented the degradation of RI, indicating that serine proteases of the SC cleave RI. Taken together, this study adds RNase 5 to the list of antimicrobial factors present in the SC and suggests that proteases contribute indirectly to the defense function of the SC by releasing the RI-mediated inhibition of RNase 5 and RNase 7.
Collapse
|
9
|
Saluja A, Kalonia DS. Nature and consequences of protein–protein interactions in high protein concentration solutions. Int J Pharm 2008; 358:1-15. [PMID: 18485634 DOI: 10.1016/j.ijpharm.2008.03.041] [Citation(s) in RCA: 150] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 03/27/2008] [Accepted: 03/28/2008] [Indexed: 11/20/2022]
Affiliation(s)
- Atul Saluja
- Process and Product Development, Amgen Inc., Seattle, WA 98119, USA
| | | |
Collapse
|
10
|
Bublitz M, Holland C, Sabet C, Reichelt J, Cossart P, Heinz DW, Bierne H, Schubert WD. Crystal structure and standardized geometric analysis of InlJ, a listerial virulence factor and leucine-rich repeat protein with a novel cysteine ladder. J Mol Biol 2008; 378:87-96. [PMID: 18343406 DOI: 10.1016/j.jmb.2008.01.100] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 01/18/2008] [Accepted: 01/22/2008] [Indexed: 02/09/2023]
Abstract
We report on the crystal structure of the internalin domain of InlJ, a virulence-associated surface protein of Listeria monocytogenes, at 2.7-A resolution. InlJ is a member of the internalin family of listerial cell surface proteins characterized by a common N-terminal domain. InlJ bears 15 leucine-rich repeats (LRRs), the same number as in InlA, the prototypical internalin family member. The LRRs of InlJ differ from those of other internalins by having 21, rather than 22, residues and by replacing 1 LRR-defining hydrophobic residue with a conserved cysteine. These cysteines stack to form an intramolecular ladder and regular hydrophobic interactions in consecutive repeats. Analyzing the curvature, twist, and lateral bending angles of InlJ and comparing these with several other LRR proteins, we provide a systematic geometric comparison of LRR protein structures (http://bragi2.helmholtz-hzi.de/Angulator/). These indicate that both cysteine and asparagine ladders stabilize the LRR fold, whereas substitutions in some repeat positions are more likely than others to induce changes in LRR geometry.
Collapse
Affiliation(s)
- Maike Bublitz
- Molecular Host Pathogen Interactions, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Johnson RJ, Lavis LD, Raines RT. Intraspecies regulation of ribonucleolytic activity. Biochemistry 2007; 46:13131-40. [PMID: 17956129 DOI: 10.1021/bi701521q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The evolutionary rate of proteins involved in obligate protein-protein interactions is slower and the degree of coevolution higher than that for nonobligate protein-protein interactions. The coevolution of the proteins involved in certain nonobligate interactions is, however, essential to cell survival. To gain insight into the coevolution of one such nonobligate protein pair, the cytosolic ribonuclease inhibitor (RI) proteins and secretory pancreatic-type ribonucleases from cow (Bos taurus) and human (Homo sapiens) were produced in Escherichia coli and purified, and their physicochemical properties were analyzed. The two intraspecies complexes were found to be extremely tight (bovine Kd = 0.69 fM; human Kd = 0.34 fM). Human RI binds to its cognate ribonuclease (RNase 1) with 100-fold greater affinity than to the bovine homologue (RNase A). In contrast, bovine RI binds to RNase 1 and RNase A with nearly equal affinity. This broader specificity is consistent with there being more pancreatic-type ribonucleases in cows (20) than humans (13). Human RI (32 cysteine residues) also has 4-fold less resistance to oxidation by hydrogen peroxide than does bovine RI (29 cysteine residues). This decreased oxidative stability of human RI, which is caused largely by Cys74, implies a larger role for human RI as an antioxidant. The conformational and oxidative stabilities of both RIs increase upon complex formation with ribonucleases. Thus, RI has evolved to maintain its inhibition of invading ribonucleases, even when confronted with extreme environmental stress. That role appears to take precedence over its role in mediating oxidative damage.
Collapse
Affiliation(s)
- R Jeremy Johnson
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706-1544, USA
| | | | | |
Collapse
|
12
|
Johnson RJ, McCoy JG, Bingman CA, Phillips GN, Raines RT. Inhibition of human pancreatic ribonuclease by the human ribonuclease inhibitor protein. J Mol Biol 2007; 368:434-49. [PMID: 17350650 PMCID: PMC1993901 DOI: 10.1016/j.jmb.2007.02.005] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 01/27/2007] [Accepted: 02/02/2007] [Indexed: 11/26/2022]
Abstract
The ribonuclease inhibitor protein (RI) binds to members of the bovine pancreatic ribonuclease (RNase A) superfamily with an affinity in the femtomolar range. Here, we report on structural and energetic aspects of the interaction between human RI (hRI) and human pancreatic ribonuclease (RNase 1). The structure of the crystalline hRI x RNase 1 complex was determined at a resolution of 1.95 A, revealing the formation of 19 intermolecular hydrogen bonds involving 13 residues of RNase 1. In contrast, only nine such hydrogen bonds are apparent in the structure of the complex between porcine RI and RNase A. hRI, which is anionic, also appears to use its horseshoe-shaped structure to engender long-range Coulombic interactions with RNase 1, which is cationic. In accordance with the structural data, the hRI.RNase 1 complex was found to be extremely stable (t(1/2)=81 days; K(d)=2.9 x 10(-16) M). Site-directed mutagenesis experiments enabled the identification of two cationic residues in RNase 1, Arg39 and Arg91, that are especially important for both the formation and stability of the complex, and are thus termed "electrostatic targeting residues". Disturbing the electrostatic attraction between hRI and RNase 1 yielded a variant of RNase 1 that maintained ribonucleolytic activity and conformational stability but had a 2.8 x 10(3)-fold lower association rate for complex formation and 5.9 x 10(9)-fold lower affinity for hRI. This variant of RNase 1, which exhibits the largest decrease in RI affinity of any engineered ribonuclease, is also toxic to human erythroleukemia cells. Together, these results provide new insight into an unusual and important protein-protein interaction, and could expedite the development of human ribonucleases as chemotherapeutic agents.
Collapse
Affiliation(s)
- R Jeremy Johnson
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, USA
| | | | | | | | | |
Collapse
|
13
|
|
14
|
Nitto T, Dyer KD, Czapiga M, Rosenberg HF. Evolution and Function of Leukocyte RNase A Ribonucleases of the Avian Species, Gallus gallus. J Biol Chem 2006; 281:25622-34. [PMID: 16803891 DOI: 10.1074/jbc.m604313200] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
In this study, we explore the evolution and function of two closely related RNase A ribonucleases from the chicken, Gallus gallus. Separated by approximately 10 kb on chromosome 6, the coding sequences of RNases A-1 and A-2 are diverging under positive selection pressure (dN > dS) but remain similar to one another (81% amino acid identity) and to the mammalian angiogenins. Immunoreactive RNases A-1 and A-2 (both approximately 16 kDa) were detected in peripheral blood granulocytes and bone marrow. Recombinant proteins are ribonucleolytically active (kcat = 2.6 and 0.056 s(-1), respectively), and surprisingly, both interact with human placental ribonuclease inhibitor. RNase A-2, the more cationic (pI 11.0), is both angiogenic and bactericidal; RNase A-1 (pI 10.2) has neither activity. We demonstrated via point mutation of the catalytic His110 that ablation of ribonuclease activity has no impact on the bactericidal activity of RNase A-2. We determined that the divergent domains II (amino acids 71-76) and III (amino acids 89-104) of RNase A-2 are both important for bactericidal activity. Furthermore, we demonstrated that these cationic domains can function as independent bactericidal peptides without the tertiary structure imposed by the RNase A backbone. These results suggest that ribonucleolytic activity may not be a crucial constraint limiting the ongoing evolution of this gene family and that the ribonuclease backbone may be merely serving as a scaffold to support the evolution of novel, nonribonucleolytic proteins.
Collapse
Affiliation(s)
- Takeaki Nitto
- Laboratory of Allergic Diseases and Research Technologies Branch, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | |
Collapse
|