download report - Istituto Pasteur

P a r t i c i p a n t s :
Patrizia Filetici, CNR researcher; Andrea Brenna, Federica
Tosi, PhD students; Eleonora Muggiano, Stefania Federico,
Alberto Gualdieri, undergraduate students.
C o l l a b o r a t i o n s :
Dipartimento di Biochimica e Biologia Molecolare, Università di
Parma (Prof. Simone Ottonello); Dipartimento di Biologia
Vegetale e Biotecnologie Agroambientali e Zootecniche,
Università di Perugia (Dr. Leonardo Baciarelli Falini); Istituto
per la Protezione delle Piante del CNR c/o Dipartimento Biologia
Vegetale, Università di Torino (Dr. Raffaella Balestrini); INRA,
Nancy, France (Dr. Francis Martin); UNAM, México DF, México
(Dr. Alicia González).
Report of activity
In Eukaryotes the association between DNA and histones
does not represent a mechanical way of condense
in a small volume thousands of genes, but constitutes
a real regolative structure. Cells differentiation
and cellular cross-talks are achieved through
specific modifications of the chromatin. In particular
histone tails are subject to several convalent posttranslation
modifications as acetylation, methylation,
phosphorylation, ubiquitinylation, sumoylation and
ADP-ribosylation. More recently a large number of
trascription factors have been observed also to be
modified (mainly by acetylation and phosphorylation)
by the same proteins operating on histones.
These proteins are associated to specific domains
(bromodomain, chromodomain, etc.) able to recognize
the modifications, therefore assuming the role of
effectors of the pathways of signal transduction. We
have mainly dedicated our attention to the acetylation,
as part of signal tranduction pathways in the
model system of Ascomycetes. We have studied,
among this class of simple Eukaryotes, three species:
S. cerevisiae, N. crassa and Tuber borchii in order to
understand the role of the HAT Gcn5 in eukaryotic
31
Molecular genetics of eukaryotes - AREA 3
Molecular machines and effectors involved in the regulation
of light response and cell cycle in simple Eukaryotes
Principal investigator: Paola Ballario
Researcher in Molecular Genetics
Dipartimento di Genetica e Biologia Molecolare
Tel: (+39) 06 49912318, 06 49912235; Fax: (+39) 06 4440812
paola.ballario@uniroma1.it
replication and transcription: a) S. cerevisiae the classical
budding yeast has been used in order to investigate
the role of one of the best characterized histone-acetyltransferase
(HAT) Gcn5 in kinetochore
(KT) and in centrosome assembly and function; b) N.
crassa a filamentous fungus that is a classical model
for the study of photobiology was the object of a
previous study (Pasteur-Cenci Bolognetti Project,
2005-2006) that demonstrated the correlation
between light induction of transcription and histone
H3 transient acetylation in the promoter of light
dependent genes. Data obtained recently demonstrated
that not only histones are substrate for
acetyltransferase but also WC-1 itself (the photoreceptor
organized as a vertebrate nuclear receptor) is
subject to acetylation by an HAT; c) Tuber spp, an
hypogeus filamentous fungus is well known since
Roman Empire for its gastronomical value, but its
life cycle is still misterious. Genetical and molecular
tools begin to be developed only now. We are analyzing
the influence of the environment, in particular of
light on T. borchii life cycle. We have settled the conditions
for truffles molecular transformation by A.
tumefaciens and we are involved in T. melanosporum
genomic sequence.
Results
A) The centromere and the KT are large complexes
constituted by more then 60 proteins evolutivelly
conserved. These complexes assembled on the
centromeric DNA exert a control on chromosome
attach by the mitotic spindle. Checkpoint activity
that blocks cellular proliferation in presence of missegregation
is linked to KT. An anomalous activity
of the KT produces chromosomal misaggregation
and aneuploidies, associated in humans to tumors
and genetic pathologies (i.e. Down and Turner syndromes).
Aim of this section of our project is to
understand the role of Gcn5 (an HAT protein) in
chromosomes segregation and, in centromere and
kinetocore structural organization in S. cerevisiae. In