All-digital transmit beamformer for portable high-frequency ultrasound imaging systems.

To meet the requirements of high-frequency ultrasound imaging systems, a transmit-beamforming integrated circuit with higher delay resolution than conventional transmit-beamforming circuits, which are typically implemented using field-programmable gate array chips, is presented. It also requires smaller volumes, allowing for portable applications. Its proposed design includes two all-digital delay-locked loops providing a specified digital control code for a counter-based beamforming delay chain (CBDC) to generate stable and suitable delays for exciting the array transducer elements without variations in process, voltage, and temperature. Moreover, to maintain the duty cycle of long propagation signals, this novel CBDC requires only a few delay cells, significantly reducing hardware costs and power consumption. Simulations were conducted, revealing a maximum time delay of 451.9 ns with a time resolution of 652 ps and a maximum lateral resolution error of 0.04 mm at 6.8 mm.

A Dual-Functional Orphan Response Regulator Negatively Controls the Differential Transcription of Duplicate groELs and Plays a Global Regulatory Role in Myxococcus.

Differential transcription of functionally divergent duplicate genes is critical for bacterial cells to properly and competitively function in the environment, but the transcriptional regulation mechanisms remain in mystery. Myxococcus xanthus DK1622 possesses two duplicate groELs with divergent functions. Here, we report that MXAN_4468, an orphan gene located upstream of groEL2, encodes a response regulator (RR) and is responsible for the differential expression regulation of duplicate groELs. This RR protein realizes its negative regulatory role via a novel dual-mode functioning manner: binding to the transcription repressor HrcA to enhance its transcriptional inhibition of duplicate groELs and binding to the 3' end of the MXAN_4468 sequence to specifically decrease the transcription of the following groEL2. Phosphorylation at the conserved 61st aspartic acid is required to trigger the regulatory functions of MXAN_4468. Pull-down experiment and mutation demonstrated that two noncognate CheA proteins, respectively belonging to the Che8 and Che7 chemosensory pathways, are involved in the protein phosphorylation. A transcriptome analysis, as well as the pull-down experiment, suggested that MXAN_4468 plays a global negative regulatory role in M. xanthus. This study elucidates, for the first time, the regulatory mechanism of differential transcription of bacterial duplicate groELs and suggests a global regulatory role of a dual-functional orphan RR. IMPORTANCE Multiply copied groELs require precise regulation of transcriptions for their divergent cellular functions. Here, we reported that an orphan response regulator (RR) tunes the transcriptional discrepancy of the duplicate groELs in Myxococcus xanthus DK1622 in a dual-functional mode. This RR protein has a conserved phosphorylation site, and the phosphorylation is required for the regulatory functions. Transcriptomic analysis, as well as a pull-down experiment, suggests that the RR plays a global regulatory role in M. xanthus. This study highlights that the dual-functional orphan RR might be involved in conducting the transcriptional symphony to stabilize the complex biological functions in cells.

Achieving High-Performance Ge0.92 Bi0.08 Te Thermoelectrics via LaB6 -Alloying-Induced Band Engineering and Multi-Scale Structure Manipulation.

In this work, a LaB6 -alloying strategy is reported to effectively boost the figure-of-merit (ZT) of Ge0.92 Bi0.08 Te-based alloys up to ≈2.2 at 723 K, attributed to a synergy of La-dopant induced band structuring and structural manipulation. Density-function-theory calculations reveal that La dopant enlarges the bandgap and converges the energy offset between the sub-valence bands in cubic-structured GeTe, leading to a significantly increased effective mass, which gives rise to a high Seebeck coefficient of ≈263 µV K-1 and in turn a superior power factor of ≈43 µW cm-1 K-2 at 723 K. Besides, comprehensive electron microscopy characterizations reveal that the multi-scale phonon scattering centers, including a high density of planar defects, Boron nanoparticles in tandem with enhanced boundaries, dispersive Ge nanoprecipitates in the matrix, and massive point defects, contribute to a low lattice thermal conductivity of ≈0.67 W m-1 K-1 at 723 K. Furthermore, a high microhardness of ≈194 Hv is witnessed in the as-designed Ge0.92 Bi0.08 Te(LaB6 )0.04 alloy, derived from the multi-defect-induced strengthening. This work provides a strategy for developing high-performance and mechanical robust middle-temperature thermoelectric materials for practical thermoelectric applications.

Optimizing Electronic Quality Factor toward High-Performance Ge1- x - y Tax Sby Te Thermoelectrics: The Role of Transition Metal Doping.

Owing to high intrinsic figure-of-merit implemented by multi-band valleytronics, GeTe-based thermoelectric materials are promising for medium-temperature applications. Transition metals are widely used as dopants for developing high-performance GeTe thermoelectric materials. Herein, relevant work is critically reviewed to establish a correlation among transition metal doping, electronic quality factor, and figure-of-merit of GeTe. From first-principle calculations, it is found that Ta, as an undiscovered dopant in GeTe, can effectively converge energy offset between light and heavy conduction band extrema to enhance effective mass at high temperature. Such manipulation is verified by the increased Seebeck coefficient of synthesized Ge1- x - y Tax Sby Te samples from 160 to 180 µV K-1 at 775 K upon doping Ta, then to 220 µV K-1 with further alloying Sb. Characterization using electron microscopy also reveals the unique herringbone structure associated with multi-scale lattice defects induced by Ta doping, which greatly hinder phonon propagation to decrease thermal conductivity. As a result, a figure-of-merit of ≈2.0 is attained in the Ge0.88 Ta0.02 Sb0.10 Te sample, reflecting a maximum heat-to-electricity efficiency up to 17.7% under a temperature gradient of 400 K. The rationalized beneficial effects stemming from Ta doping is an important observation that will stimulate new exploration toward high-performance GeTe-based thermoelectric materials.

The Regulation of LexA on UV-Induced SOS Response in Myxococcus xanthus Based on Transcriptome Analysis.

SOS response is a conserved response to DNA damage in prokaryotes and is negatively regulated by LexA protein, which recognizes specifically an "SOS-box" motif present in the promoter region of SOS genes. Myxococcus xanthus DK1622 possesses a lexA gene, and while the deletion of lexA had no significant effect on either bacterial morphology, UV-C resistance, or sporulation, it did delay growth. UV-C radiation resulted in 651 upregulated genes in M. xanthus, including the typical SOS genes lexA, recA, uvrA, recN and so on, mostly enriched in the pathways of DNA replication and repair, secondary metabolism, and signal transduction. The UV-irradiated lexA mutant also showed the induced expression of SOS genes and these SOS genes enriched into a similar pathway profile to that of wild-type strain. Without irradiation treatment, the absence of LexA enhanced the expression of 122 genes that were not enriched in any pathway. Further analysis of the promoter sequence revealed that in the 122 genes, only the promoters of recA2, lexA and an operon composed of three genes (pafB, pafC and cyaA) had SOS box sequence to which the LexA protein is bound directly. These results update our current understanding of SOS response in M. xanthus and show that UV induces more genes involved in secondary metabolism and signal transduction in addition to DNA replication and repair; and while the canonical LexA-dependent regulation on SOS response has shrunk, only 5 SOS genes are directly repressed by LexA.

Structural Evolution of High-Performance Mn-Alloyed Thermoelectric Materials: A Case Study of SnTe.

Mn alloying in thermoelectrics is a long-standing strategy for enhancing their figure-of-merit through optimizing electronic transport properties by band convergence, valley perturbation, or spin-orbital coupling. By contrast, mechanisms by which Mn contributes to suppressing thermal transports, namely thermal conductivity, is still ambiguous. A few precedent studies indicate that Mn introduces a series of hierarchical defects from the nano- to meso-scale, leading to effective phonon scattering scoping a wide frequency spectrum. Due to insufficient insights at the atomic level, the theory remains as phenomenological and cannot be used to quantitatively predict the thermal conductivity of Mn-alloyed thermoelectrics. Herein, by choosing the SnTe as a case study, aberration-corrected transmission electron microscopy (TEM)/scanning transmission electron microscopy (STEM) to characterize the lattice complexity of Sn1.02- x Mnx Te is employed. Mn as a "dynamic" dopant that plays an important role in SnTe with respect to different alloying levels or post treatments is revealed. The results indicate that Mn precipitates at x = 0.08 prior to reaching solubility (≈10 mol%), and then splits into MnSn substitution and γ-MnTe hetero-phases via mechanical alloying. Understanding such unique crystallography evolution, combined with a modified Debye-Callaway model, is critical in explaining the decreased thermal conductivity of Sn1.02- x Mnx Te with rational phonon scattering pathways, which should be applicable for other thermoelectric systems.

Digitally Controlled Oscillator with High Timing Resolution and Low Complexity for Clock Generation.

This paper presents a digitally controlled oscillator (DCO) with a low-complexity circuit structure that combines multiple delay circuits to achieve a high timing resolution and wide output frequency range simultaneously while also significantly reducing the overall power consumption. A 0.18 µm complementary metal-oxide-semiconductor standard process was used for the design, and measurements showed that the chip had a minimum controllable timing resolution of 4.81 ps and power consumption of 142 µW with an output signal of 364 MHz. When compared with other designs using advanced processes, the proposed DCO demonstrated the best power-to-frequency ratio. Therefore, it can output a signal at the required frequency more efficiently in terms of power consumption. Additionally, because the proposed DCO uses digital logic gates only, a cell-based design flow can be implemented. Hence, the proposed DCO is not only easy to implement in different processes but also easy to integrate with other digital circuits.

Two PAAR Proteins with Different C-Terminal Extended Domains Have Distinct Ecological Functions in Myxococcus xanthus.

Bacterial proline-alanine-alanine-arginine (PAAR) proteins are located at the top of the type VI secretion system (T6SS) nanomachine and carry and deliver effectors into neighboring cells. Many PAAR proteins are fused with a variable C-terminal extended domain (CTD). Here, we report that two paar-ctd genes (MXAN_RS08765 and MXAN_RS36995) located in two homologous operons are involved in different ecological functions of Myxococcus xanthusMXAN_RS08765 inhibited the growth of plant-pathogenic fungi, while MXAN_RS36995 was associated with the colony-merger incompatibility of M. xanthus cells. These two PAAR-CTD proteins were both toxic to Escherichia coli cells, while MXAN_RS08765, but not MXAN_RS36995, was also toxic to Saccharomyces cerevisiae cells. Their downstream adjacent genes, i.e., MXAN_RS08760 and MXAN_RS24590, protected against the toxicities. The MXAN_RS36995 protein was demonstrated to have nuclease activity, and the activity was inhibited by the presence of MXAN_RS24590. Our results highlight that the PAAR proteins diversify the CTDs to play divergent roles in M. xanthusIMPORTANCE The type VI secretion system (T6SS) is a bacterial cell contact-dependent weapon capable of delivering protein effectors into neighboring cells. The PAAR protein is located at the top of the nanomachine and carries an effector for delivery. Many PAAR proteins are extended with a diverse C-terminal sequence with an unknown structure and function. Here, we report two paar-ctd genes located in two homologous operons involved in different ecological functions of Myxococcus xanthus; one has antifungal activity, and the other is associated with the kin discrimination phenotype. The PAAR-CTD proteins and the proteins encoded by their downstream genes form two toxin-immunity protein pairs. We demonstrated that the C-terminal diversification of the PAAR-CTD proteins enriches the ecological functions of bacterial cells.

Psychroflexus aurantiacus sp. nov., isolated from soil in the Yellow River Delta wetlands.

A Gram-stain-negative, strictly aerobic, non-motile, orange-coloured bacterium, designated YR1-1T, was isolated from a soil sample collected from the Yellow River Delta wetlands (PR China). Growth was observed at a salinity of 1.0-15.0 % NaCl, 4-45 °C and pH 6.0-9.0. The results of phylogenetic analysis based on the 16S rRNA gene sequences indicated that YR1-1T represented a member of the genus Psychroflexus, with the highest sequence similarity to Psychroflexus sediminis YIM-C238T (97.9 %), followed by Psychroflexus aestuariivivens (97.1 %) and Psychroflexus torquis (96.4 %). The average nucleotide identity and digital DNA-DNA hybridization values between YR1-1T and other closely related type strains of species of the genus Psychroflexus were 68.7-86.3% and 17.8-30.9 %. The genome of the strain was 2 899 374 bp in length with 39.8 % DNA G+C content. The predominant fatty acids (>10 %) were iso-C15 : 0 and anteiso-C15 : 0. The major respiratory quinone was menaquinone-6 (MK-6) and the major polar lipids were phosphatidylethanolamine, phospholipid, diphosphatidylglycerol, two unidentified aminolipids and four unidentified lipids. The combined genotypic and phenotypic data indicate that YR1-1T represents a novel species within the genus Psychroflexus, for which the name Psychroflexus aurantiacus sp. nov., is proposed. The type strain is YR1-1T (=KCTC 72794T=CGMCC 1.17458T).

Deinococcus terrestris sp. nov., a gamma ray- and ultraviolet-resistant bacterium isolated from soil.

Strain SDU3-2T was isolated from a soil sample collected in Shandong Province, PR China. Cells of SDU3-2T were spherical, Gram-stain-positive, aerobic and non-motile. Cellular growth of the strain occurred at 25-45 °C, pH 5.5-8.5 and with 0-1.5 % (w/v) of NaCl. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain SDU3-2T was closest to the type strain Deinococcus murrayi ALT-1bT with a similarity of 95.2 %. The draft genome was 3.49 Mbp long with 69.2 mol% G+C content. Strain SDU3-2T exhibited high resistance to gamma radiation (D10 >12 kGy) and UV (D10 >900 J m-2). The strain encoded many genes for resistance to radiation and oxidative stress, which were highly conserved with other Deinococcus species, but possessed interspecific properties. The major fatty acids of SDU3-2T cells were C15 : 1 ω6c, C16 : 1 ω7c/C16 : 1 ω6c, and C17 : 1 ω8c, the major menaquinone was menaquinone-8, and the major polar lipids were an unidentified phosphoglycolipid, four unidentified glycolipids and an unidentified phospholipid. The average nucleotide identity and DNA-DNA hybridization results further indicated that strain SDU3-2T represents a new species in the genus Deinococcus, for which the name Deinococcus terrestris sp. nov. is proposed. The type strain is SDU3-2T (=CGMCC 1.17147T=KCTC 43098T).

32-Channel transmit beamformer with high timing resolution for high-frequency ultrasound imaging systems.

This paper presents a 32-channel high timing resolution transmit-beamforming circuit for use in high-frequency ultrasound imaging systems. Conventional transmit-beamforming circuits are typically implemented using field-programmable gate array (FPGA) chips. However, it is difficult for FPGAs to provide high timing resolution to meet the beamforming requirements of high-frequency ultrasound imaging systems. The proposed transmit-beamforming design can generate stable and suitable delays to excite 32-channel array transducer elements without variations in the process, voltage, and temperature. In addition, the proposed low-complexity architecture can maintain the duty cycle of long prorogation signals with low hardware cost to meet the timing requirements of a large channel number array transducer. The proposed designed transmit beamformer uses 0.18-µm CMOS technology for a 30-MHz high-frequency linear array, and the simulation results show that the proposed transmit-beamforming application-specific integrated circuit can achieve a maximum time delay of 619.5 ns with a time resolution of 617 ps.

Functional Division Between the RecA1 and RecA2 Proteins in Myxococcus xanthus.

Myxococcus xanthus DK1622 has two RecA genes, recA1 (MXAN_1441) and recA2 (MXAN_1388), with unknown functional differentiation. Herein, we showed that both recA genes were induced by ultraviolet (UV) irradiation but that the induction of recA1 was more delayed than that of recA2. Deletion of recA1 did not affect the growth but significantly decreased the UV-radiation survival, homologous recombination (HR) ability, and induction of LexA-dependent SOS genes. In contrast, the deletion of recA2 markedly prolonged the lag phase of bacterial growth and increased the sensitivity to DNA damage caused by hydrogen peroxide but did not change the UV-radiation resistance or SOS gene inducibility. Protein activity analysis demonstrated that RecA1, but not RecA2, catalyzed DNA strand exchange (DSE) and LexA autocleavage in vitro. Transcriptomic analysis indicated that RecA2 has evolved mainly to regulate gene expression for cellular transportation and antioxidation. This is the first report of functional divergence of duplicated bacterial recA genes. The results highlight the evolutionary strategy of M. xanthus cells for DNA HR and genome sophistication.

Insights into the persistence and phenotypic effects of the endogenous and cryptic plasmid pMF1 in its host strain Myxococcus fulvus 124B02.

Many endogenous plasmids carry no noticeable benefits for their bacterial hosts, and the persistence of these 'cryptic plasmids' and their functional impacts are mostly unclear. In this study, we investigated these uncertainties using the social bacterium Myxococcus fulvus 124B02 and its endogenous plasmid pMF1. pMF1 possesses diverse genes that originated from myxobacteria, suggesting a longstanding co-existence of the plasmid with various myxobacterial species. The curing of pMF1 from 124B02 had almost no phenotypic effects on the host. Laboratory evolution experiments showed that the 124B02 strain retained pMF1 when subcultured on dead Escherichia coli cells but lost pMF1 when subcultured on living E. coli cells or on casitone medium; these results indicated that the persistence of pMF1 in 124B02 was environment-dependent. Curing pMF1 caused the mutant to lose the ability to predate and develop fruiting bodies more quickly than the pMF1-containing strain after they were subcultured on dead E. coli cells, which indicated that the presence of pMF1 in M. fulvus 124B02 has some long-term effects on its host. The results provide some new insights into the persistence and impacts of cryptic plasmids in their natural bacterial cells.

Whole transcriptome analysis and gene deletion to understand the chloramphenicol resistance mechanism and develop a screening method for homologous recombination in Myxococcus xanthus.

BACKGROUND: Myxococcus xanthus DK1622 is a model system for studying multicellular development, predation, cellular differentiation, and evolution. Furthermore, it is a rich source of novel secondary metabolites and is widely used as heterologous expression host of exogenous biosynthetic gene clusters. For decades, genetic modification of M. xanthus DK1622 has mainly relied on kanamycin and tetracycline selection systems. RESULTS: Here, we introduce an alternative selection system based on chloramphenicol (Cm) to broaden the spectrum of available molecular tools. A chloramphenicol-resistant growth phase and a chloramphenicol-susceptible growth phase before and after chloramphenicol-induction were prepared, and later sequenced to identify specific genes related to chloramphenicol-repercussion and drug-resistance. A total of 481 differentially expressed genes were revealed in chloramphenicol-resistant Cm5_36h and 1920 differentially expressed genes in chloramphenicol-dormant Cm_8h. Moreover, the gene expression profile in the chloramphenicol-dormant strain Cm_8h was quite different from that of Cm5_36 which had completely adapted to Cm, and 1513 differentially expression genes were identified between these two phenotypes. Besides upregulated acetyltransferases, several transporter encoding genes, including ABC transporters, major facilitator superfamily transporters (MFS), resistance-nodulation-cell division (RND) super family transporters and multidrug and toxic compound extrusion family transporters (MATE) were found to be involved in Cm resistance. After the knockout of the most highly upregulated MXAN_2566 MFS family gene, mutant strain DK-2566 was proved to be sensitive to Cm by measuring the growth curve in the Cm-added condition. A plasmid with a Cm resistance marker was constructed and integrated into chromosomes via homologous recombination and Cm screening. The integration efficiency was about 20% at different concentrations of Cm. CONCLUSIONS: This study provides a new antibiotic-based selection system, and will help to understand antibiotic resistance mechanisms in M. xanthus DK1622.

Dual-cell structure digitally controlled oscillator with portability for clock generation applications.

This paper presents a dual-cell structure and cell-based design digitally controlled oscillator (DCO) for high-performance clock generation applications. The proposed dual-cell DCO not only can reduce the intrinsic delay to increase the maximum output frequency significantly but also extend the controllable range. In addition, the proposed digitally controlled delay cell uses the cascading structure to realize the wide output frequency range and high timing resolution at the same time. A DCO chip is fabricated in 0.18 µm CMOS technology, and the core area is 0.003 mm2. Measurement results show that operation range is from 169 MHz to 522 MHz and the finest delay resolution is 2.2 ps. Furthermore, because the proposed DCO is implemented with the digital standard cells, it is a portable design to migrate to different processes easily and reduce design time significantly.

Comparison of Treatment Response and Survival Profiles Between Drug-Eluting Bead Transarterial Chemoembolization and Conventional Transarterial Chemoembolization in Chinese Hepatocellular Carcinoma Patients: A Prospective Cohort Study.

This study evaluated the difference in treatment response and survival profiles between drug-eluting bead transarterial chemoembolization (DEB-TACE) and conventional transarterial chemoembolization (cTACE) treatments in Chinese hepatocellular carcinoma (HCC) patients. A total of 120 HCC patients were consecutively enrolled in this prospective cohort study, which showed that DEB-TACE achieved higher complete response (CR) (30.8%) compared with cTACE (7.4%) with no difference in overall response rate (ORR) for patients treated with DEB-TACE and cTACE (80.8% vs. 73.5%). In addition, DEB-TACE was associated with a lower rate of progressive disease (PD) compared with cTACE (1.9% vs. 11.8%). With respect to survival, patients in the DEB-TACE group achieved median progression-free survival (PFS) of 15 months (95% CI 12-18 months), which was longer than the cTACE group [median PFS 11 months (95% CI 10-12 months)]. Median overall survival (OS) was also longer with DEB-TACE [25 months (95% CI 22-28 months)] when compared with cTACE [21 months (95% CI 18-24 months)]. Univariate and multivariate logistic regression analysis showed that DEB-TACE was an independent predictive factor for achieving CR. Univariate Cox's regression analysis revealed that DEB-TACE was a predictive factor for prolonged PFS and OS, while multivariate analysis demonstrated that DEB-TACE was not an independent factor for predicting PFS or OS. In conclusion, we found that DEB-TACE achieved higher treatment response and prolonged survival compared with cTACE in Chinese HCC patients.

Phylogeny-guided characterization of glycosyltransferases for epothilone glycosylation.

Glycosylation of natural products can influence their pharmacological properties, and efficient glycosyltransferases (GTs) are critical for this purpose. The polyketide epothilones are potent anti-tumour compounds, and YjiC is the only reported GT for the glycosylation of epothilone. In this study, we phylogenetically analysed 8261 GTs deposited in CAZy database and revealed that YjiC locates in a subbranch of the Macrolide I group, forming the YjiC-subbranch with 160 GT sequences. We demonstrated that the YjiC-subbranch GTs are normally efficient in epothilone glycosylation, but some showed low glycosylation activities. Sequence alignment of YjiC-subbranch showed that the 66th and 77th amino acid residues, which were close to the catalytic cavity in molecular docking model, were conserved in five high-active GTs (Q66 and P77) but changed in two low-efficient GTs. Site-directed residues swapping at the two positions in the two low-active GTs (BssGT and BamGT) and the high-active GT BsGT-1 demonstrated that the two amino acid residues played an important role in the catalytic efficiency of epothilone glycosylation. This study highlights that the potent GTs for appointed compounds are phylogenetically grouped with conserved residues for the catalytic efficiency.

Genome Editing in Model Strain Myxococcus xanthus DK1622 by a Site-Specific Cre/loxP Recombination System.

Myxococcus xanthus DK1622 is a rich source of novel secondary metabolites, and it is often used as an expression host of exogenous biosynthetic gene clusters. However, the frequency of obtaining large genome-deletion variants by using traditional strategies is low, and progenies generated by homologous recombination contain irregular deletions. The present study aims to develop an efficient genome-engineering system for this bacterium based on the Cre/loxP system. We first verified the functionality of the native cre system that was integrated into the chromosome with an inducible promoter PcuoA. Then we assayed the deletion frequency of 8-bp-spacer-sequence mutants in loxP by Cre recombinase which was expressed by suicide vector pBJ113 or self-replicative vector pZJY41. It was found that higher guanine content in a spacer sequence had higher deletion frequency, and the self-replicative vector was more suitable for the Cre/loxP system, probably due to the leaky expression of inducible promoter PcuoA. We also inspected the effects of different antibiotics and the native or synthetic cre gene. Polymerase chain reaction (PCR) and sequencing of new genome joints confirmed that the Cre/loxP system was able to delete a 466 kb fragment in M. xanthus. This Cre/loxP-mediated recombination could serve as an alternative genetic manipulation method.

CIRCE element evolved for the coordinated transcriptional regulation of bacterial duplicate groELs.

Chaperonin groEL genes are duplicated in approximately 20% of bacteria, and the duplicates are differentially transcribed due to their divergent functions. The coordinated regulation of this differential transcription is as yet undetermined. In this study, we reported that the controlling inverted repeat of chaperone expression (CIRCE) element (the HrcA-binding site located upstream of the promoter) evolved for the transcriptional regulation of duplicate groELs. CIRCE composition and locations were found to be phylogenetically conserved in bacterial taxa. Myxococcus xanthus DK1622 has two CIRCE elements (CIRCE1groESL1 and CIRCE2groESL1) in the promoter region of groESL1 and one CIRCE element (CIRCEgroEL2) before groEL2. We also found that negative HrcA and positive ?32 regulators coordinated the transcription of duplicate groELs, and that the double deletion in DK1622 eliminated transcriptional differences and reduced the heat-shock responses of groELs. In vitro binding assays showed that HrcA protein binding was biased towards CIRCE1groESL1, followed by CIRCEgroEL2, but that HrcA proteins failed to bind with CIRCE2groESL1. Mutation experiments revealed that single-nucleotide mutations in the inverted repeat regions changed the HrcA-binding abilities of CIRCEs. We constructed an in vivo transcription-regulation system in Escherichia coli to pair each of the regulators with a groEL promoter. The results indicated that the transcriptional regulation performed by HrcA and ?32 was biased towards the groEL2 and groEL1 promoters, respectively. Based on promoter-sequence characteristics, we proposed a model of the coordinated regulation of the transcription of duplicate groELs in M. xanthus DK1622.