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Identification of Maize (Zea Mays L.) Genes Encoding Telomere Repeat DNA-Binding Proteins

Title: Identification of Maize (Zea Mays L.) Genes Encoding Telomere Repeat DNA-Binding Proteins.
Name(s): Marian, Calin O., author
Bass, Hank W., professor directing dissertation
Levenson, Cathy W., outside committee member
Hurt, Myra M., committee member
Keller, Laura R., committee member
Bates, George W., committee member
Department of Biological Science, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: Text
Issuance: monographic
Date Issued: 2005
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
Physical Form: online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: In order to understand the molecular basis of meiotic telomere behavior, we have set out to identify genes that encode proteins with telomere repeat DNA-binding activity in maize (Zea mays L.), a model organism system. Using a combination of sequence similarity searches and DNA hybridization library screens we have isolated, sequenced, and characterized several full-length cDNA clones that resulted in the identification of two new gene families. These are the Single Myb histone (Smh) and the Terminal acidic SANT (Tacs) gene families. The Smh genes encode small (~32 kDa), basic proteins with a unique triple motif structure consisting of an N-terminal SANT/Myb-like domain, a centrally located linker histone H1 globular domain, and a coiled-coil dimerization domain near the C terminus. The SMH proteins appear to be unique to the plant kingdom and are encoded by small gene families in Arabidopsis, rice, and the PcMYB1 gene of parsley. The Smh1 gene is expressed in leaves and maps genetically to chromosome 8 (bin 8.05), with a duplicate locus on chromosome 3 (bin 3.09). A recombinant full-length SMH1, rSMH1, was found by band-shift assays to bind double-stranded oligonucleotide probes with at least two internal tandem copies of the maize telomere repeat, TTTAGGG. Point mutations in the telomere repeat residues reduced or abolished the binding, whereas rSMH1 bound nonspecifically to single-stranded DNA probes. We focused next on a second class of plant genes, which encode ~45 kDa proteins with a C-terminal acidic SANT (SWI3, ADA2, N-COR, and TFIIIB B') domain. A full-length cDNA from a juvenile leaf and shoot mRNA library was chosen for further analysis and named Terminal acidic SANT 1 (Tacs1). Polymorphic Tacs1 PCR products from genomic DNA map to the genetic bin 2.08. The Tacs1 gene structure and predicted protein sequence are nearly identical to those of the rice ANTHER INDEHISCENCE1 (AID1) gene of rice, indicating that maize Tacs1 and rice AID1 are homologous genes. Analysis of maize EST databases revealed that Tacs1 mRNA is found at relatively low levels, limited to very young reproductive organs, such as the primordia of ear and tassel shoots. The SANT domain is similar in sequence and structure to the DNA-binding domain (DBD) of Myb-related proteins, but the SANT domain exhibits an acidic surface chemistry that may impart a different function to this domain. The SANT domain of the maize TACS1 protein exhibits an acidic isoelectric point and a negative electrostatic surface potential. The discovery of these two plant gene families will help decipher the protein composition of plant telomeres and shed some light on telomere functions associated with some of these proteins.
Identifier: FSU_migr_etd-2741 (IID)
Submitted Note: A Dissertation submitted to the Department of Biological Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Degree Awarded: Summer Semester, 2005.
Date of Defense: June 24, 2005.
Keywords: Telomeres, Maize, Myb-like Domain, SANT Domain
Bibliography Note: Includes bibliographical references.
Advisory Committee: Hank W. Bass, Professor Directing Dissertation; Cathy W. Levenson, Outside Committee Member; Myra M. Hurt, Committee Member; Laura R. Keller, Committee Member; George W. Bates, Committee Member.
Subject(s): Biology
Persistent Link to This Record:
Owner Institution: FSU

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Marian, C. O. (2005). Identification of Maize (Zea Mays L.) Genes Encoding Telomere Repeat DNA-Binding Proteins. Retrieved from