• The Plant Pathology Journal
• /
• 제31권4호
• /
• pp.323-333
• /
• 2015

As sessile organisms, plants are exposed to persistently changing stresses and have to be able to interpret and respond to them. The stresses, drought, salinity, chemicals, cold and hot temperatures, and various pathogen attacks have interconnected effects on plants, resulting in the disruption of protein homeostasis. Maintenance of proteins in their functional native conformations and preventing aggregation of non-native proteins are important for cell survival under stress. Heat shock proteins (HSPs) functioning as molecular chaperones are the key components responsible for protein folding, assembly, translocation, and degradation under stress conditions and in many normal cellular processes. Plants respond to pathogen invasion using two different innate immune responses mediated by pattern recognition receptors (PRRs) or resistance (R) proteins. HSPs play an indispensable role as molecular chaperones in the quality control of plasma membrane-resident PRRs and intracellular R proteins against potential invaders. Here, we specifically discuss the functional involvement of cytosolic and endoplasmic reticulum (ER) HSPs/chaperones in plant immunity to obtain an integrated understanding of the immune responses in plant cells.

• 생명과학회지
• /
• 제17권12호
• /
• pp.1760-1765
• /
• 2007

생명체 내에서 일어나는 거의 모든 반응은 단백질이 촉진하거나 수행한다. 단백질은 세포질과 소포체에서 합성될 때 엄격하게 조절된다. 그러나, 새로이 합성된 모든 단백질이 살아남아서 생명을 유지시키는 기능에 관여하게 되지는 않는다. 가장 알맞은 생리학적 in vitro 실험 조건에서 새로이 합성된 단백질의 약 3분의 1 정도는 합성되자마자 proteasome에 의해 빠르게 분해된다고 보고되었다. 또한, 단백질은 합성이 성공적으로 이루어진 이후에는 3차원 구조를 갖기 위해 접힘(folding)이 이루어져야 하고, subunit들은 assembly 과정을 거쳐야 비로소 성숙된 단백질로서 기능을 하게 된다. 어떤 단백질군은 자연적으로 접힘이 일어나는 반면 어떤 단백질군은 분자 샤페론(molecular chaperones)과 folding enzymes의 도움을 받아야만 접힘이 일어난다. 분자 샤페론은 세포 전역에 분포하고 있으며, 세균에서부터 고등 동식물에 이르기까지 모든 생명체에 존재한다. 이들 중 Hsp70군은 많이 연구된 분자 샤페론으로서 지난 10여년 동안 조절인자들이 새로이 발견되어 작용 mechanism이 보다 자세히 밝혀졌다. 본 총설에서 Hsp70군과 그 조절인자들에 대한 전반적인 서술을 하였으며, 이들의 기능이 분자 샤페론 기능 외에 생체 내에서 중요한 기능들이 새롭게 밝혀지고 있어 이들의 작용 mechanism을 조명함으로 이해를 돕고자 한다.

• 한국미생물·생명공학회지
• /
• 제36권2호
• /
• pp.149-157
• /
• 2008

Many proteins consist of distinctive domains that can act independently or cooperatively to achieve a unique function. As these domains evolve from a naturally existing repertoire of functional domains, this implies that domain organization is an intrinsic element involved in building the complex structure and function of proteins. Thus, identifying functional domains would appear to be critical to the elucidation of questions related to protein evolution, folding, and the engineering of hybrid proteins for tai- lored applications. However, the simple application of "Lego-like assembly" to the engineering of hybrid proteins is an oversimplification, as many hybrid constructs lack structural stability, usually due to unfavorable domain contacts. Thus, directed evolution, along with computational studies, may help to engineer hybrid proteins with improved physico-chemical properties. Accordingly, this paper introduces several approaches to functional hybrid protein engineering that potentially can be used to create modulators of gene transcription and cell signaling, and novel biosensors to analyze biological functions in vivo.

• Molecules and Cells
• /
• 제43권11호
• /
• pp.899-908
• /
• 2020

Intrinsically disordered proteins or regions (IDPs or IDRs) are widespread in the eukaryotic proteome. Although lacking stable three-dimensional structures in the free forms, IDRs perform critical functions in various cellular processes. Accordingly, mutations and altered expression of IDRs are associated with many pathological conditions. Hence, it is of great importance to understand at the molecular level how IDRs interact with their binding partners. In particular, discovering the unique interaction features of IDRs originating from their dynamic nature may reveal uncharted regulatory mechanisms of specific biological processes. Here we discuss the mechanisms of the macromolecular interactions mediated by IDRs and present the relevant cellular processes including transcription, cell cycle progression, signaling, and nucleocytoplasmic transport. Of special interest is the multivalent binding nature of IDRs driving assembly of multicomponent macromolecular complexes. Integrating the previous theoretical and experimental investigations, we suggest that such IDR-driven multiprotein complexes can function as versatile allosteric switches to process diverse cellular signals. Finally, we discuss the future challenges and potential medical applications of the IDR research.

• Molecules and Cells
• /
• 제27권6호
• /
• pp.657-665
• /
• 2009

The ovomucoid pre-mRNA has been folded into mini-hairpins adaptable for the RNA recognition motif (RRM) protein binding. The number of mini-hairpins were 372 for pre-mRNA and 83-86 for mature mRNA. The spatial arrangements are, in average, 16 nucleotides per mini-hairpin which includes 7 nt in the stem, 5.6 nt in the loop and 3.7 nt in the inter-hairpin spacer. The constitutive splicing system of ovomucoid-pre-mRNA is characterized by preferred order of intron removal of 5/6 > 7/4 > 2/1 > 3. The 5' splice sites (5'SS), branch point sequences (BPS) and 3' splice sites (3'SS) were identified and free energies involved have been estimated in 7 splice sites. Thermodynamic barriers for splice sites from the least (|lowest| -Kcal) were 5, 4, 7, 6, 2, 1, and 3; i.e., -18.7 Kcal, -20.2 Kcal, -21.0 Kcal, -24.0 Kcal, - 25.4 Kcal, -26.4 Kcal and -28.2 Kcal respectively. These are parallel to the kinetic data of splicing order reported in the literature. As a result, the preferred order of intron removals can be described by a consideration of free energy changes involved in the spliceosomal assembly pathway. This finding is consistent with the validity of hnRNP formation mechanisms in previous reports.

• Journal of Microbiology and Biotechnology
• /
• 제18권2호
• /
• pp.299-307
• /
• 2008

Soybean seed ferritin is essential for human iron supplementation and iron deficiency anemia prevention because it contains abundant bioavailable iron and is frequently consumed in the human diet. However, it is poorly understood in regards its several properties, such as iron mineralization, subunit assembly, and protein folding. To address these issues, we decided to prepare the soybean seed ferritin complex via a recombinant DNA approach. In this paper, we report a rapid and simple Escherichia coli expression system to produce the soybean seed ferritin complex. In this system, two subunits of soybean seed ferritin, H-2 and H-1, were encoded in a single plasmid, and optimal expression was achieved by additionally coexpressing a team of molecular chaperones, trigger factor and GroEL-GroES. The His-tagged ferritin complex was purified by $Ni^{2+}$ affinity chromatography, and an intact ferritin complex was obtained following His-tagged enterokinase (His-EK) digestion. The purified ferritin complex synthesized in E. coli demonstrated some reported features of its native counterpart from soybean seed, including an apparent molecular weight, multimeric assembly, and iron uptake activity. We believe that the strategy described in this paper may be of general utility in producing other recombinant plant ferritins built up from two types of subunits.

• 폴리머
• /
• 제30권6호
• /
• pp.453-463
• /
• 2006

분자 모델에 의한 전산 모사는 단백질 접힘, 미셀화, 블록공중합체의 규칙구조화 등 다양한 고분자 계의 자기조립 현상을 예측하거나 그 조립 메커니즘을 밝히는 데 특별히 유용한 연구방법이다. 자기조립 현상은 분자 수, 분자 크기 등, 계의 속성에 따라 나노미터 이하의 현상으로부터 마이크론이나 그 이상의 길이 스케일의 현상까지 조립 구조의 길이 스케일이 매우 광범위하기 때문에 다양한 계의 모든 조립 현상을 양자역학적 방법과 같은 궁극의 근본원칙에 의해 모사하는 것은 현실적인 시간 내에서 불가능하다. 이러한 문제들을 해결하기 위해 계를 기술하는 과정에서 필요 이상으로 세밀한 표현을 생략하여 모델을 다른 관점에서 재구성하는 방법이 있는데 재구성된 모델은 그 관점에 따라 크게 '원자 수준'의 모델과 '메조 스케일 수준'의 모델로 분류할 수 있다. 본 총론에서는 고분자 자기조립 현상과 관련하여 이 두 가지 관점에 따른 모델과 모사 방법들에 대해 살펴보고자 한다.

• International Journal of Industrial Entomology and Biomaterials
• /
• 제23권2호
• /
• pp.223-229
• /
• 2011

Cyclophilins are originally identified as cytosolic binding protein of the immunosuppressive drug cyclosporine A. They have an activity of peptidyl prolyl cis/trans-isomerases (PPIase), which may play important roles in protein folding, trafficking, assembly and cell signaling. In this study, we report the cloning and characterization of a Bombyx mori cyclophilin A (bCypA) cDNA. The full-length cDNA of bCypA consist of 947 nucleotides with a polyadenylation signal sequence AATAAA and contain an open reading frame of 498 nucleotides encoding a polypeptide of 166 amino acids. The deduced amino acid sequence of bCypA shares a central peptidyl prolyl cis/trans-isomerase and a cyclosporin-A-binding domain with other cyclophilin sequences. Relative quantification real-time (RT) PCR analysis shows that mRNA transcripts of bCypA are detected in all the investigated tissues and highest expression level in the skin of 3-day-old 5 instar larva. Also, bCypA had PPIase activity on the proline-containing peptides. Accordingly, we suggest that bCypA is a new member of the cyclophilin A (CyPA) family and will be useful for quality control of bioactivity recombinant proteins with proline-containing peptides.

• Molecules and Cells
• /
• 제44권10호
• /
• pp.758-769
• /
• 2021

Calcium homeostasis modulator 1 (CALHM1) is a membrane protein with four transmembrane helices that form an octameric ion channel with voltage-dependent activation. There are four conserved cysteine (Cys) residues in the extracellular domain that form two intramolecular disulfide bonds. We investigated the roles of C42-C127 and C44-C161 in human CALHM1 channel biogenesis and the ionic current (I_CALHM1). Replacing Cys with Ser or Ala abolished the membrane trafficking as well as I_CALHM1. Immunoblotting analysis revealed dithiothreitol-sensitive multimeric CALHM1, which was markedly reduced in C44S and C161S, but preserved in C42S and C127S. The mixed expression of C42S and wild-type did not show a dominant-negative effect. While the heteromeric assembly of CALHM1 and CALHM3 formed active ion channels, the co-expression of C42S and CALHM3 did not produce functional channels. Despite the critical structural role of the extracellular cysteine residues, a treatment with the membrane-impermeable reducing agent tris(2-carboxyethyl) phosphine (TCEP, 2 mM) did not affect I_CALHM1 for up to 30 min. Interestingly, incubation with TCEP (2 mM) for 2-6 h reduced both I_CALHM1 and the surface expression of CALHM1 in a time-dependent manner. We propose that the intramolecular disulfide bonds are essential for folding, oligomerization, trafficking and maintenance of CALHM1 in the plasma membrane, but dispensable for the voltage-dependent activation once expressed on the plasma membrane.

• 생명과학회지
• /
• 제31권6호
• /
• pp.568-573
• /
• 2021

본 연구는 전장 유전체 연관성 분석(genome-wide association study, GWAS)을 통해 ERp29의 mRNA 발현과 관련된 유전좌위(expression quantitative trait loci, eQTL)을 식별하는 것을 목표로 하였다. 대상 유전자는 ERp29이다. ERp29는 소포체(ER)의 lumen에 단백질의 folding & assembly 기능을 가진 분자 chaperone 단백질로서 소포체 스트레스에 의해 발현량이 증가하며, 분비 단백질의 생합성에 관여한다. 최근 연구 결과 발암과 연관성이 알려지면서 주목을 받고 있다. 총 373명의 유럽인의 genome을 대상으로 GWAS 분석 결과, ERp29 유전자 발현은 정소와 뇌에서 강하게 발현하는 long noncoding RNA (LncRNA) LOC105372577과 관계가 있었다. 즉, 3개의 eQTL: rs6138266 (p<4.172e10-9), rs62193420 (p<1.173e10-8), rs6138267 (p<2.041e10-8)와 연관성이 깊은 것으로 밝혀졌다. ERp29의 발현과 연관이 있는 것으로 확인된 3개의 eQTL을 사용한 transcriptome-wide association study (TWAS) 결과 osteosarcoma amplified 9 (OS9) 발현과 유의한 연관성을 보이며 OS9 유전자의 up-stream에 upstream of transcription factor 1 (USF1)이 결합할 수 있는 것을 알았다.