Perez-Jannotti RM, et al 2001 reported two forms of mitochondrial DNA ligase III are produced in Xenopus laevis
oocytes.
Full-length cDNAs for DNA ligase IV and the a and b isoforms of DNA ligase III were cloned
from Xenopus laevis to permit study of the genes encoding mitochondrial DNA ligase. DNA
ligase IIIa and IIIb share a common N-terminus that encodes a mitochondrial localization signal
capable of targeting green fluorescent protein to mitochondria while the N-terminus of DNA
ligase IV does not. RT-PCR analyses with adult frog tissues demonstrate that while DNA ligase
IIIa and DNA ligase IV are ubiquitously expressed, DNA ligase IIIb expression is restricted to
testis and ovary. Mitochondrial lysates from Xenopus laevis oocytes contain both DNA ligase
IIIa and IIIb but no detectable DNA ligase IV. Gel filtration, sedimentation, native gel
electrophoresis and in vitro cross-linking experiments demonstrate that mtDNA ligase IIIa exists
as a high molecular weight complex. We discuss the possibility that DNA ligase IIIa exists in
mitochondria in association with novel mitochondrial protein partners or as a homodimer.
NCBI Summary:
Eukaryotes, in contrast to prokaryotes, contain more than one DNA ligase, and these enzymes have distinct roles in DNA metabolism. Five DNA ligase activities, I-V, have been purified from mammalian cell extracts. Ligase III is more closely related to the DNA ligase encoded by pox viruses, than to replicative DNA ligases, such as mammalian DNA ligase 1, and thus may be involved in DNA repair and recombination. Two biochemically distinct isoforms of ligase III, alpha and beta, encoding polypeptides with different C-terminal amino acids have been identified, and result from alternative splicing of precursor mRNA.
General function
Oncogenesis, Tumor suppressor
Comment
Cellular localization
Nuclear
Comment
Ovarian function
Germ cell development
Comment
Expression regulated by
Comment
Ovarian localization
Primordial Germ Cell
Comment
Global gene expression analysis in fetal mouse ovaries with and without meiosis and comparison of selected genes with meiosis in the testis. Olesen C et al. In order to identify novel genes involved in early meiosis and early ovarian development in the mouse, we used microarray technology to compare transcriptional activity in ovaries without meiotic germ cells at embryonic age 11.5 (E11.5) and E13.5 ovaries with meiosis. Overall, 182 genes were differentially expressed; 134 were known genes and 48 were functionally uncharacterized. A comparison of our data with the literature associated, for the first time, at least eight of the known genes with female meiosis/germ cell differentiation (Aldh1a1, C2pa, Tex12, Stk31, Lig3, Id4, Recql, Piwil2). These genes had previously only been described in spermatogenesis. The microarray also detected an abundance of vesicle-related genes of which four were upregulated (Syngr2, Stxbp1, Ric-8, SytIX) and one (Myo1c) was downregulated in E13.5 ovaries. Detailed analysis showed that the temporal expression of SytIX also coincided with the first meiotic wave in the pubertal testis. This is the first time that SytIX has been reported in non-neuronal tissue. Finally, we examined the expression of one of the uncharacterized genes and found it to be gonad-specific in adulthood. We named this novel transcript 'Gonad-expressed transcript 1' (Get-1). In situ hybridization showed that Get-1 was expressed in meiotic germ cells in both fetal ovaries and mature testis. Get-1 is therefore a novel gene in both male and female meiosis.