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401.
Biegel E Schmidt S González JM Müller V 《Cellular and molecular life sciences : CMLS》2011,68(4):613-634
Microbes have a fascinating repertoire of bioenergetic enzymes and a huge variety of electron transport chains to cope with
very different environmental conditions, such as different oxygen concentrations, different electron acceptors, pH and salinity.
However, all these electron transport chains cover the redox span from NADH + H+ as the most negative donor to oxygen/H2O as the most positive acceptor or increments thereof. The redox range more negative than −320 mV has been largely ignored.
Here, we have summarized the recent data that unraveled a novel ion-motive electron transport chain, the Rnf complex, that
energetically couples the cellular ferredoxin to the pyridine nucleotide pool. The energetics of the complex and its biochemistry,
as well as its evolution and cellular function in different microbes, is discussed. 相似文献
402.
Thomae AW Baltin J Pich D Deutsch MJ Ravasz M Zeller K Gossen M Hammerschmidt W Schepers A 《Cellular and molecular life sciences : CMLS》2011,68(22):3741-3756
In eukaryotes, binding of the six-subunit origin recognition complex (ORC) to DNA provides an interactive platform for the
sequential assembly of pre-replicative complexes. This process licenses replication origins competent for the subsequent initiation
step. Here, we analyze the contribution of human Orc6, the smallest subunit of ORC, to DNA binding and pre-replicative complex
formation. We show that Orc6 not only interacts with Orc1–Orc5 but also with the initiation factor Cdc6. Biochemical and imaging
experiments reveal that this interaction is required for licensing DNA replication competent. Furthermore, we demonstrate
that Orc6 contributes to the interaction of ORC with the chaperone protein HMGA1a (high mobility group protein A1a). Binding
of human ORC to replication origins is not specified at the level of DNA sequence and the functional organization of origins
is poorly understood. We have identified HMGA1a as one factor that might direct ORC to AT-rich heterochromatic regions. The
systematic analysis of the interaction between ORC and HMGA1a revealed that Orc6 interacts with the acidic C-terminus of HMGA1a
and also with its AT-hooks. Both domains support autonomous replication if targeted to DNA templates. As such, Orc6 functions
at different stages of the replication initiation process. Orc6 can interact with ORC chaperone proteins such as HMGA1a to
facilitate chromatin binding of ORC and is also an essential factor for pre-RC formation. 相似文献
403.
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406.
In 1905, Albert Einstein proposed that the forces that cause the random Brownian motion of a particle also underlie the resistance
to macroscopic motion when a force is applied. This insight, of a coupling between fluctuation (stochastic behavior) and responsiveness
(non-stochastic behavior), founded an important branch of physics. Here we argue that his insight may also be relevant for
understanding evolved biological systems, and we present a ‘fluctuation–response relationship’ for biology. The relationship
is consistent with the idea that biological systems are similarly canalized to stochastic, environmental, and genetic perturbations.
It is also supported by in silico evolution experiments, and by the observation that ‘noisy’ gene expression is often both
more responsive and more ‘evolvable’. More generally, we argue that in biology there is (and always has been) an important
role for macroscopic theory that considers the general behavior of systems without concern for their intimate molecular details. 相似文献
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409.
The maintenance of mucosal barrier equilibrium in the intestine requires a delicate and dynamic balance between enterocyte
loss by apoptosis and the generation of new cells by proliferation from stem cell precursors at the base of the intestinal
crypts. When the balance shifts towards either excessive or insufficient apoptosis, a broad range of gastrointestinal diseases
can manifest. Recent work from a variety of laboratories has provided evidence in support of a role for receptors of the innate
immune system, including Toll-like receptors 2, 4, and 9 as well as the intracellular pathogen recognition receptor NOD2/CARD15,
in the initiation of enterocyte apoptosis. The subsequent induction of enterocyte apoptosis in response to the activation
of these innate immune receptors plays a key role in the development of various intestinal diseases, including necrotizing
enterocolitis, Crohn’s disease, ulcerative colitis, and intestinal cancer. This review will detail the regulatory pathways
that govern enterocyte apoptosis, and will explore the role of the innate immune system in the induction of enterocyte apoptosis
in gastrointestinal disease. 相似文献
410.
Lubka-Pathak M Shah AA Gallozzi M Müller M Zimmermann U Löwenheim H Pfister M Knipper M Blin N Schimmang T 《Cellular and molecular life sciences : CMLS》2011,68(16):2739-2749