The 5' coding region of Paramecium surface antigen genes controls mutually exclusive transcription.

Leeck, C L; Forney, James D.

doi:10.1073/pnas.93.7.2838

Cited by 22 publications

(14 citation statements)

References 30 publications

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“…Surface antigen genes are organized as a multigene family and a common feature of this system is their mutually exclusive expression—only one surface antigen is expressed at a time, which is called the serotype (Beale 1954; Sonneborn 1947). Whether this phenomenon is controlled at a genetic level is not entirely clear, but 5′‐coding regions of the genes play a role in mutual exclusive expression (Leeck and Forney 1994, 1996). …”

mentioning

confidence: 99%

Variety of Serotypes of Paramecium primaurelia: Single Epitopes are Responsible for Immunological Differentiation

Simón

Schmidt

2005

J Eukaryotic Microbiology

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Paramecium primaurelia expresses three major types of surface antigens. We report here the identification of the gene for serotype S, which completes the sequence data of expressed serotypes of P. primaurelia. The complete open reading frame of surface antigen S was identified using a novel technique, based upon the presence of conservative regions in the non-coding areas of the multigene family. We were able to isolate the 7194-bp-long open reading frame from the macronuclear DNA for Serotype 156S. The corresponding mRNA was detected in the two serotype S-expressing stocks, 60 and 156, of P. primaurelia, which clarifies that both stocks are using the same S allele. Comparisons of the nucleic acid and the deduced amino-acid sequence showed high identity to surface antigen 51B of P. tetraurelia, sufficient to cause an immunological cross-reaction in vivo. Immunologically relevant epitopes in vivo were identified in the central regions of the genes, constructed of nearly perfect tandem repeats.

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confidence: 99%

Variety of Serotypes of Paramecium primaurelia: Single Epitopes are Responsible for Immunological Differentiation

Simón

Schmidt

2005

J Eukaryotic Microbiology

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“…Analyses of chimeric A-51 and B-51 transgenes have shown that the 5Ј-upstream region of the A-51 gene is required for transcription but is not sufficient for mutual exclusion (23). The element responsible for mutual exclusion is at least in part located in the 5Ј coding region, substitution of which allowed coexpression of A-51 with B-51 (22). Furthermore, introduction of a frameshift mutation in this chimeric gene reduced the rate of transcription of the corresponding gene (41).…”

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confidence: 99%

Analysis of Paramecium tetraurelia A-51 Surface Antigen Gene Mutants Reveals Positive-Feedback Mechanisms for Maintenance of Expression and Temperature-Induced Activation

Matsuda

Forney

2005

Eukaryot Cell

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In Paramecium tetraurelia, variable surface antigen loci show mutually exclusive expression which is controlled primarily at the transcriptional level. Clonally stable expression of a single antigen has attracted models involving self-regulation by their gene products. However, direct demonstration of self-feedback at the molecular level has been complicated due to the inability to separate the functional gene from its product as well as copy number effects associated with injected extrachromosomal DNA in the polygenomic somatic nucleus. In this study, we exploited several germ line termination and frameshift mutations in the A-51 surface antigen gene to analyze variable surface antigen expression. These mutant alleles have the same copy number as the wild-type allele and therefore eliminate possible copy number effects. The mutant alleles were not transcribed at 27°C, consistent with positive-feedback models for gene expression. However, further analysis showed that high temperatures (34°C) induced transcription of the mutant A genes even in the presence of a different antigen on the cell surface. Thus, transcription was temperature dependent. Unlike wild-type cells, transcription of the mutant A genes at high temperatures was not maintained after temperature shift back to 27°C in homozygous mutant cells. Importantly, transcription of the mutant allele was maintained at 27°C in heterozygous cells with one copy of the wild-type allele. These results indicate that expression of the wild-type gene is required to stabilize its own transcriptional state at 27°C.Heritable traits of eukaryotic cells are not always governed by DNA sequence information in the nucleus. Examples of heritable traits independent from DNA information include higher-order chromatin structures (18,20

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“…Although the molecular basis for expression of Paramecium serotype genes has been clariˆed to some extent for 51A [18][19][20] which has been identiˆed as another serotype showing an aging-dependent expression pattern, 5) this paper is theˆrst report concerning the 51D gene and so far no relevance in the underlying events for gene expression has been observed between the two serotypes.…”

Section: Puriˆcation Of a Dna-binding Protein Speciˆc To The A-51d Genementioning

confidence: 96%

Transcriptional Regulators of the 51D Surface Protein Gene ofParamecium tetraurelia

Tanabe

Haraguchi

Yoshioka

2002

Bioscience, Biotechnology, and Biochemistry

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The 5' coding region of Paramecium surface antigen genes controls mutually exclusive transcription.

Abstract: ABSTRACT

Cited by 22 publications

References 30 publications

Variety of Serotypes of Paramecium primaurelia: Single Epitopes are Responsible for Immunological Differentiation

Variety of Serotypes of Paramecium primaurelia: Single Epitopes are Responsible for Immunological Differentiation

Analysis of Paramecium tetraurelia A-51 Surface Antigen Gene Mutants Reveals Positive-Feedback Mechanisms for Maintenance of Expression and Temperature-Induced Activation

Transcriptional Regulators of the 51D Surface Protein Gene ofParamecium tetraurelia

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