Crystal structure of KPC-2:: Insights into carbapenemase activity in class a β-lactamases
Crystal structure of KPC-2:: Insights into carbapenemase activity in class a β-lactamases
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DOI：
10.1021/bi700300u
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发表时间：
2007-05-15
期刊：
影响因子：
2.9
通讯作者：
van den Akker, Focco
中科院分区：
文献类型：
--
作者：
Ke, Wei;Bethel, Christopher R.;van den Akker, Focco
-内酰胺酶使-内酰胺类抗生素失活，是抗生素耐药性的主要原因。最近爆发的肺炎克雷伯菌碳青霉烯耐药（KPC）感染由KPC型β -内酰胺酶介导，对我们的“最后手段”抗生素碳青霉烯类造成严重威胁。KPC， β -内酰胺酶是丝氨酸碳青霉烯酶，是a类β -内酰胺酶的一个亚类，它已经进化到能够有效水解碳青霉烯类和头孢霉素，这些碳青霉烯类和头孢霉素在靠近羰基的α位置上含有取代，通常使这些β -内酰胺类耐水解。为了研究这种碳青霉烯酶活性的分子基础，我们在1.85埃分辨率下确定了KPC-2的结构。KPC-2的活性位点显示存在双碱缓冲分子，该缓冲分子通过其羧基与保守的活性位点残基S130、K234、T235和T237相互作用；这些可能类似于-内酰胺羧基部分在Michaelis - Menten复合体中产生的相互作用。将KPC-2结构与非碳青霉烯酶和先前确定的NMC-A和sme1碳青霉烯酶结构进行比较，发现碳青霉烯酶中有几个独特的活性位点改变。催化S70残基的向外移动使得碳青霉烯酶的活性位点更浅，可能使更大的底物更容易接近。除了假设的羧基结合袋的协同运动外，N132和N170的移位可能会为α取代基提供进一步的空间，这可能使底物以稍微不同的角度结合以容纳α取代基。KPC-2的结构为新出现的A类β -内酰胺酶的碳青霉烯酶活性提供了关键的见解。
beta-Lactamases inactivate beta-lactam antibiotics and are a major cause of antibiotic resistance. The recent outbreaks of Klebsiella pneumoniae carbapenem resistant (KPC) infections mediated by KPC type beta-lactamases are creating a serious threat to our "last resort" antibiotics, the carbapenems. KPC,beta-lactamases are serine carbapenemases and are a subclass of class A beta-lactamases that have evolved to efficiently hydrolyze carbapenems and cephamycins which contain substitutions at the alpha-position proximal to the carbonyl group that normally render these beta-lactams resistant to hydrolysis. To investigate the molecular basis of this carbapenemase activity, we have determined the structure of KPC-2 at 1.85 angstrom resolution. The active site of KPC-2 reveals the presence of a bicine buffer molecule which interacts via its carboxyl group with conserved active site residues S130, K234, T235, and T237; these likely resemble the interactions the beta-lactam carboxyl moiety makes in the Michaelis - Menten complex. Comparison of the KPC-2 structure with non-carbapenemases and previously determined NMC-A and SME-1 carbapenemase structures shows several active site alterations that are unique among carbapenemases. An outward shift of the catalytic S70 residue renders the active sites of the carbapenemases more shallow, likely allowing easier access of the bulkier substrates. Further space for the alpha-substituents is potentially provided by shifts in N132 and N170 in addition to concerted movements in the postulated carboxyl binding pocket that might allow the substrates to bind at a slightly different angle to accommodate these alpha-substituents. The structure of KPC-2 provides key insights into the carbapenemase activity of emerging class A beta-lactamases.