<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="6.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Inácio, José Manuel</style></author><author><style face="normal" font="default" size="100%">Isabel de Sá-Nogueira</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">&lt;a href=&quot;http://jb.asm.org/content/190/12/4272.full&quot; target=&quot;_blank&quot;&gt;Characterization of &lt;i&gt;abn2 (yxiA)&lt;/i&gt;, Encoding a &lt;i&gt;Bacillus subtilis&lt;/i&gt; GH43 Arabinanase, Abn2, and Its Role in Arabino-Polysaccharide Degradation&lt;/a&gt;</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Bacteriology</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2008</style></year></dates><number><style face="normal" font="default" size="100%">12</style></number><volume><style face="normal" font="default" size="100%">190</style></volume><pages><style face="normal" font="default" size="100%">4272-4280</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p style=&quot;text-align:justify&quot;&gt;The extracellular depolymerization of arabinopolysaccharides by microorganisms is accomplished by arabinanases, xylanases, and galactanases. Here, we characterize a novel endo-α-1,5-L-arabinanase (EC 3.2.1.99) from &lt;i&gt;Bacillus subtilis&lt;/i&gt;, encoded by the &lt;i&gt;yxiA&lt;/i&gt; gene (herein renamed &lt;i&gt;abn2&lt;/i&gt;) that contributes to arabinan degradation. Functional studies by mutational analysis showed that Abn2, together with previously characterized AbnA, is responsible for the majority of the extracellular arabinan activity in &lt;i&gt;B. subtilis&lt;/i&gt;. Abn2 was overproduced in &lt;i&gt;Escherichia coli&lt;/i&gt;, purified from the periplasmic fraction, and characterized with respect to substrate specificity and biochemical and physical properties. With linear-α-1,5-l-arabinan as the preferred substrate, the enzyme exhibited an apparent K&lt;sub&gt;m&lt;/sub&gt; of 2.0 mg ml&lt;sup&gt;−1&lt;/sup&gt; and V&lt;sub&gt;max&lt;/sub&gt; of 0.25 mmol min&lt;sup&gt;−1&lt;/sup&gt; mg&lt;sup&gt;−1&lt;/sup&gt; at pH 7.0 and 50°C. RNA studies revealed the monocistronic nature of &lt;i&gt;abn2&lt;/i&gt;. Two potential transcriptional start sites were identified by primer extension analysis, and both a σ&lt;sup&gt;A&lt;/sup&gt;-dependent and a σ&lt;sup&gt;H&lt;/sup&gt;-dependent promoter were located. Transcriptional fusion studies revealed that the expression of &lt;i&gt;abn2&lt;/i&gt; is stimulated by arabinan and pectin and repressed by glucose; however, arabinose is not the natural inducer. Additionally, &lt;i&gt;trans&lt;/i&gt;-acting factors and &lt;i&gt;cis&lt;/i&gt; elements involved in transcription were investigated. Abn2 displayed a control mechanism at a level of gene expression different from that observed with AbnA. These distinct regulatory mechanisms exhibited by two members of extracellular glycoside hydrolase family 43 (GH43) suggest an adaptative strategy of &lt;i&gt;B. subtilis&lt;/i&gt; for optimal degradation of arabinopolysaccharides.&lt;/p&gt;
</style></abstract><notes><style face="normal" font="default" size="100%">&lt;p&gt;n/a&lt;/p&gt;
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