ÿþ<HTML><HEAD><TITLE>25º Congresso Brasileiro de Microbiologia </TITLE><link rel=STYLESHEET type=text/css href=css.css></HEAD><BODY aLink=#ff0000 bgColor=#FFFFFF leftMargin=0 link=#000000 text=#000000 topMargin=0 vLink=#000000 marginheight=0 marginwidth=0><table align=center width=700 cellpadding=0 cellspacing=0><tr><td align=left bgcolor=#cccccc valign=top width=550><font face=arial size=2><strong><font face=Verdana, Arial, Helvetica, sans-serif size=3><font size=1>25º Congresso Brasileiro de Microbiologia </font></font></strong><font face=Verdana size=1><b><br></b></font><font face=Verdana, Arial,Helvetica, sans-serif size=1><strong> </strong></font></font></td><td align=right bgcolor=#cccccc valign=top width=150><font face=arial size=2><strong><font face=Verdana, Arial, Helvetica, sans-serif size=1><font  size=1>ResumoID:2144-2</font></em></font></strong></font></td></tr><tr><td colspan=2><br><br><table align=center width=700><tr><td>Área: <b>Genética e Biologia Molecular ( Divisão N )</b><p align=justify><strong>
  MOLECULAR CLONING, OVERPRODUCTION AND CHARACTERIZATION OF <SPAN STYLE="FONT-STYLE: ITALIC;">MYCOBACTERIUM TUBERCULOSIS </SPAN>IMP DEHYDROGENASE (EC 1.1.1.205)      
</strong></p><p align=justify><b><u>Thiago Milech de Assunção </u></b>  (<i>INCT-TB</i>); <b>Cristopher  Schneider </b>  (<i>INCT-TB</i>); <b>Luiz Augusto  Basso </b>  (<i>INCT-TB</i>); <b>Diógenes  Santiago Santos </b>  (<i>INCT-TB</i>)<br><br></p><b><font size=2>Resumo</font></b><p align=justify class=tres><font size=2>

<p class="MsoNormal" style="text-align: justify; line-height: 150%;"><i style=""><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">Mycobacterium tuberculosis</span></i><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">,
the agent of human tuberculosis (TB), causes about 2 million deaths per year. It
is estimated by the World Health Organization that one-third of the world s
population is infected with <i style="">M.
tuberculosis</i> in a latent form. Furthermore, the increasing emergence of
multidrug-resistant strains has complicated the treatment and control of TB. Knowledge
of the mode of action and role of purine <i style="">de
novo</i> pathway enzymes in <i style="">M.
tuberculosis</i>, which are required for mycobacterial growth, could reveal new
targets for the rational design of potent and selective </span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">anti-TB </span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">agents that might be active
against drug-resistant strains. Inosine monophosphate dehydrogenase (IMPDH)
catalyzes the nicotinamide-adenine dinucleotide (NAD<sup>+</sup>)-dependent
oxidation of inosine 5 -monophosphate (IMP) to xanthosine 5 -monophosphate
(XMP). </span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">Because
this enzyme acts on the synthesis of purine nucleotides at a critical step, it
can be essential for mycobacterial growth</span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">. </span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">The goal of this work </span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">is to study and understand the kinetics and
biochemistry of the recombinant IMPDH enzyme from <i style="">M. tuberculosis</i>. </span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">The complete DNA coding sequence of IMPDH
(EC 1.1.1.205) from <i style="">M. tuberculosis</i>
was obtained using genomic DNA in standard polymerase chain reaction (PCR) conditions.
The amplified fragment was cloned into the pCR-Blunt vector and subcloned into
the <i><span style="">&nbsp;</span>Nde</i>I/<i>Hin</i>dIII
polylinker region of the pET-23a (+) prokaryotic expression vector. </span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">Nucleotide sequence of the
cloned fragment was determined by automated DNA sequencing. The recombinant
plasmid was then subjected to different expression tests in different <i>Escherichia
coli</i> strains. The enzyme was expressed in <i style="">E. coli</i> BL21 (DE3) cells in the soluble fraction, providing sufficient
material for purification by FPLC, biochemistry assays, determination of its
three-dimensional structure and study of its key enzymological properties.</span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"> These
results have important implications for understanding the purine metabolism of
the TB bacillus and </span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US">will serve as an initial step toward the future rational design of
specific inhibitors and drugs for this <i style="">M.
tuberculosis</i> enzyme.</span><span style="font-size: 12pt; line-height: 150%;" lang="EN-US"><o:p></o:p></span></p></font></p><br><b>Palavras-chave: </b>&nbsp;Inosine Monophosphate Dehydrogenase, Mycobacterium tuberculosis, Purine metabolism</td></tr></table></tr></td></table></body></html>