Advances in Biophysics

Based on three-dimensional structure of proteins, a rational strategy to design the protein function by physical perturbation method was proposed and tested on one of the well-examined enzymes, thermolysin for higher catalytic activity. An attempt was made to change the electrostatic potential and the dynamic property of three-dimensional structure around the active sites by single-amino-acid mutations, and the physical property of the mutants was then evaluated. Several mutants were found to have remarkably higher enzymatic activity than wild type. The multiple mutation was introduced and the logarithm of the activity was found to be almost additive. A ten times higher active mutant was realized by simultaneously introducing three single-mutations. This strategy can be easily extended to not only other enzymes but also other kinds of proteins than enzymes to modify or control the protein function based on their three-dimensional structures.

S KIDOKORO

Design of protein function by physical perturbation method

物理扰动方法设计蛋白质功能

N SASAKI

Structure-mutation analysis of the ATPase site of Dictyostelium discoideum myosin II

盘基网柄菌肌球蛋白II的ATP酶位点结构-突变分析

Three loop structures called the P-loop, switch I loop and switch II loop of myosin are major components of its ATPase site, and share structural and functional homology with the loop structures in other ATPases and GTPases such as kinesin and G-protein. Using the alanine scanning mutagenesis, structure-function relationship of the switch I and switch II loops in Dictyostelium myosin II was examined. Based on crystal structures of Dictyostelium myosin motor domain, functions of each residue in those loops are discussed.

K SUTOH

Structure-mutation analysis of the ATPase site of myosin II

肌球蛋白II的ATPase位点结构-突变分析

A high-resolution electron cryo-microscope equipped with a top-entry specimen stage has been refined by modifying a previously described superfluid helium stage. Instruments equipped with such a cryo-stage achieve a resolution of better than 2.0 Å and have proved extremely powerful in the high-resolution structure analysis of membrane proteins. Improvement of the electron microscopic system in combination with improved specimen preparation techniques allowed the structure of bR to be analyzed to a resolution of 3.0 Å. The 3D structure of bR, especially the surface features, revealed the structural basis for the efficient guidance of protons to the entrance of the transmembrane channel. Based on the characteristic difference of the atomic scattering factors for electrons of ionized atoms versus neutral atoms as well as the data analysis, charged and uncharged amino acid residues could be discriminated. Thus, electron crystallography is providing us with new and exciting insights into the structure of membrane proteins because it not only enables us to determine the structure of a membrane protein, but allows us to study its interaction with the surrounding lipid molecules and to determine its ionization state.

Y FUJIYOSHI

The structural study of membrane proteins by electron crystallography

电子晶体学在膜蛋白结构研究中的应用

物理扰动法设计蛋白质功能

A WADA

In Memory of Dr. Koscak Maruyama: The Path of His Scientific Research and Ideas

纪念Koscak Maruyama博士：他的科研之路与思想

The Tol2 element of the medaka fish is a member of the hAT (hobo/Activator/Tam3) transposable element family. About 20 copies are present in the medaka fish genome and, unlike many other hAT family elements, virtually all the copies are autonomous or potentially autonomous, containing an intact transposase gene. Excision of Tol2 is not precise at the nucleotide sequence level, excision footprints being heterogeneous. In more than half of excision events, however, breakage and rejoining of DNA molecules occur within the 8-bp target site duplication region, removing the entire Tol2 sequence and retaining parts of the target site duplications. In the reminder of the excision events, either the left or the right terminal region is left and the other end is lost together with its flanking region. Thus, there might be two different mechanisms of excision. Insertion of Tol2 occurs without detectable preference for target sequences and creates a target site duplication of exactly 8 bp. In addition to the medaka fish and related fish species, Tol2 transposes in mammalian cells in culture, including human and mouse examples. Autonomy is also retained in these cases. A gene transfer vector using Tol2 has already been established in fish. Foreign DNA fragements inserted in Tol2 can be efficiently delivered to the chromosomes by transposition. The latest version of the vector contains, between the Tol2 terminal regions, a bacterial drug-resistance gene and a plasmid replication origin. This allows simple recovery of insertion regions, as plasmid DNA, from genomic DNA of transformants. Modification of this system for other vertebrates, especially for mammals, are now in progress.

Akihiko Koga

Transposition mechanisms and biothechnology applications of the medaka fish transposable element

青鳉鱼转座元件的转座机制及其生物技术应用

S EBASHI

H NODA

Preface

前言

H IKEDA

S IIDA

E OHTSUBO

Preface to volume 38

第38卷序言

The isolation of the NBS1 gene revealed the molecular mechanisms of DSB repair. In response to DNA damage, histone H2AX in the vicinity of DSBs is phosphorylated by ATM. NBS1 then targets the MRE11/RAD50 complex to the sites of DSBs through interaction of the FHA/BRCT domain with γ-H2AX. NBSI complex binds to damaged-DNA directly, and HR repair is initiated. To collaborate DSB repair, ATM also regulates cell cycle checkpoints at GI, G2, and intra-S phases via phosphorylation of SMC, CHK2 and FANCD2. The phosphorylation of these proteins require NBS1 complex. Thus, NBSI has at least two important roles in genome maintenance, as a DNA repair protein in HR pathway and as a signal modifier in intra-S phase checkpoints. NBSI is also known to be involved in maintenance of telomores, which have DSB-like structures and defects here can cause telomcric fusion. Therefore, NBS1 should be a multi-functional protein for the maintenance of genomic integrity. Further studies on NBS1 will provide insights into the mechanisms of DNA damage response and the network of these factors involved in genomic stability.

涉及主题	生物化学生物化学遗传学物理医学细胞生物学生物物理学基因有机化学量子力学材料科学哲学内科学核磁共振
出版信息	出版商: Japan Scientific Societies Press，出版周期: Annual，期刊类型: journal，开源期刊: 否
基本数据	创刊年份: 2003，原创研究文献占比: 0.00%，自引率:N.A.， Gold OA占比: 0.00%
平均录用比例	网友分享经验：容易

Advances in Biophysics

期刊引文格式

有 1 位以上作者的期刊

有 2 位作者的期刊

有 3 位作者的期刊

有 5 位以上作者的期刊

书籍引用格式

学位论文引用格式

网页引用格式

专利引用格式

手工熬夜修改参考文献？研飞自动匹配期刊，一键轻松成稿，支持 Word/WPS

投稿经验分享

Design of protein function by physical perturbation method

Structure-mutation analysis of the ATPase site of Dictyostelium discoideum myosin II

Structure-mutation analysis of the ATPase site of myosin II

The structural study of membrane proteins by electron crystallography

Design of protein function by physical perturbation method

In Memory of Dr. Koscak Maruyama: The Path of His Scientific Research and Ideas

Transposition mechanisms and biothechnology applications of the medaka fish transposable element

Preface

Preface to volume 38

Nijmegen breakage syndrome and DNA double strand break repair by NBS1 complex