Severity: Warning
Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 143
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 143
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 209
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 994
Function: getPubMedXML
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3134
Function: GetPubMedArticleOutput_2016
File: /var/www/html/application/controllers/Detail.php
Line: 574
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 488
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
The respiratory cytochrome bc(1) complex is a fundamental enzyme in biological energy conversion. It couples electron transfer from ubiquinol to cytochrome c with generation of proton motive force which fuels ATP synthesis. The complex from the α-proteobacterium Paracoccus denitrificans, a model for the medically relevant mitochondrial complexes, lacked structural characterization. We show by LILBID mass spectrometry that truncation of the organism-specific, acidic N-terminus of cytochrome c(1) changes the oligomerization state of the enzyme to a dimer. The fully functional complex was crystallized and the X-ray structure determined at 2.7-Å resolution. It has high structural homology to mitochondrial complexes and to the Rhodobacter sphaeroides complex especially for subunits cytochrome b and ISP. Species-specific binding of the inhibitor stigmatellin is noteworthy. Interestingly, cytochrome c(1) shows structural differences to the mitochondrial and even between the two Rhodobacteraceae complexes. The structural diversity in the cytochrome c(1) surface facing the ISP domain indicates low structural constraints on that surface for formation of a productive electron transfer complex. A similar position of the acidic N-terminal domains of cytochrome c(1) and yeast subunit QCR6p is suggested in support of a similar function. A model of the electron transfer complex with membrane-anchored cytochrome c(552), the natural substrate, shows that it can adopt the same orientation as the soluble substrate in the yeast complex. The full structural integrity of the P. denitrificans variant underpins previous mechanistic studies on intermonomer electron transfer and paves the way for using this model system to address open questions of structure/function relationships and inhibitor binding.
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Source |
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http://dx.doi.org/10.1016/j.bbabio.2011.09.017 | DOI Listing |
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